histedit: drop fallback to empty string from rendertemplate() AFAICT, `cmdutil.rendertemplate()` always returns bytes (never e.g. `None`), so we don't need to fall back to empty (byte-)string. The fallback has been there since the code was added in 11c076786d56 (histedit: add templating support to histedit's rule file generation, 2019-01-29). Differential Revision: https://phab.mercurial-scm.org/D9244

phases: convert registernew users to use revision sets Differential Revision: https://phab.mercurial-scm.org/D9233

phases: allow registration and boundary advancement with revision sets The core internals either use revision sets already or can trivially use them. Use the new interface in cg1unpacker.apply to avoid materializing the list of all new nodes as it is normally just a revision range. This avoids about 67 Bytes / changeset on AMD64 in peak RSS. Differential Revision: https://phab.mercurial-scm.org/D9232

revlog: extend addgroup() with callback for duplicates The addgroup() interface currently doesn't allow the caller to keep track of duplicated nodes except by looking at the returned node list. Add an optional second callback for this purpose and change the return type to a boolean. This allows follow-up changes to use more efficient storage for the node list in places that are memory-sensitive. Differential Revision: https://phab.mercurial-scm.org/D9231

tags: add safety check for len(record) while reading hgtagsfnodescache I am trying to fix a breakage where somehow we end up getting a node of 12 length from `getfnode()`. Understanding the hgtagsfnodescache code, it seems highly unlikely that it can happen unless one of `mctx.readfast().get()` or `ctx.filenode()` is returning a node of 12 length. For safety, I think it's better to add a check to make sure that record which we are parsing is of same length we are expecting otherwise we consider that as invalid record. Differential Revision: https://phab.mercurial-scm.org/D9169

procutil: allow to specify arbitrary stdin bytes to runbgcommand For automatic clonebundles generation I need to pass arbitrary large amount of data to the process (eg: common nodes, target nodes). I am updating the `runbgcommand` to allow for this. Previously not stdin input was possible, now, one can provide raw bytes and they will be feed to the command through an unnamed temporary files. Differential Revision: https://phab.mercurial-scm.org/D9212

clonebundle: move the manifest filename to a constant I am about to add more reference to it, so I would rather have it an explicit constant. This allow to unify various call too. Differential Revision: https://phab.mercurial-scm.org/D9209

clonebundles: move a bundle of clone bundle related code to a new module In the process on general clone bundle automatically, we need to make some function available more widely. This is a good opportunity to extract a significant amount of code from `mercurial.exchange` into a new `mercurial.bundlecaches`. This make `mercurial.exchange` move under the 3K line range (hooray…). The module is called `bundlecaches` because I expect it to be eventually useful for more than just clone bundle (like pull bunbles). Differential Revision: https://phab.mercurial-scm.org/D9208

config: add a .hg/hgrc-not-shared which won't be shared in share-safe mode Previous patches add a safe mode for sharing repositories which involve sharing of source requirements and config files. In certain situations we might need to add a config to source repository which we does not want to share. For this, we add a `.hg/hgrc-not-shared` which won't be shared. This also adds a `--non-shared` flag to `hg config` command to see the non-shared config. Differential Revision: https://phab.mercurial-scm.org/D8673

dispatch: load shared source repository config in share-safe mode It seems to me now that there are two steps when config is loaded: 1) on dispatch 2) repository object creation Recent patches added functionality that there can be shares in share-safe mode where config of the source repository is shared with the the shares. However we missed adding logic to read the source config on dispatch. This leads to extensions not being loaded on dispatch and hence extensions command not being recognized. This patch fixes it by reading the shared source config on dispatch. Differential Revision: https://phab.mercurial-scm.org/D9047

tests: add test showing broken extension loading in case of share-safe When we are using share-safe and loading source repository config, we are still not loading the extensions which are enabled in the source repository. This patch demonstrates the bug. Meanwhile it also shows how unreliable `hg debugextensions` is. Differential Revision: https://phab.mercurial-scm.org/D9046

dirstate-tree: simplify the control flow in the Node.insert method But explicitly with the special case early, laying out the various case become simpler. (The initial motivation was to make some future lifetime error simpler). Differential Revision: https://phab.mercurial-scm.org/D9203

revlog: use LRU for the chain cache For a large repository, this reduces the number of filelog instances and associated data a lot. For a 1% speed penalty, it reduces peak RSS by 20% for the full NetBSD test repository. Differential Revision: https://phab.mercurial-scm.org/D9235

tests: add notes about broken `hg log --follow <file>` with copies in extras I also removed some unnecessary `#if no-changeset` where the `#else` was the same :P Differential Revision: https://phab.mercurial-scm.org/D9204

config: move message about leading spaces in config to config.py When the config parser raises a ParseError, it uses the line that failed to parse as the error message. It doesn't currently tell the user anything about why it failed to parse. b13b99d39a46 (config: highlight parse error caused by leading spaces (issue3214), 2014-03-16) added a checked based on the error *message* having leading spaces. That has worked fine because only the config parser uses the line itself as error message (I think the revset and fileset parsers use more user-friendly proper messages). It still feels like a hack. Let's make the config parser give a useful message about leading whitespace instead. We should ideally follow up with more useful messages for other parse errors in config files. Differential Revision: https://phab.mercurial-scm.org/D9241

errors: name arguments to ParseError constructor As with similar previous patches, this is to improve readability. Differential Revision: https://phab.mercurial-scm.org/D9240

errors: remove unnecessary override of __bytes__ in RevlogError StorageError already provides the same definition. Differential Revision: https://phab.mercurial-scm.org/D9234

commit: leverage cmdutil.check_incompatible_arguments() Differential Revision: https://phab.mercurial-scm.org/D9218

split: use default one-line summary Differential Revision: https://phab.mercurial-scm.org/D9255

phabsend: use default one-line summary This means that the `phabricator.node` and `phabricator.desc` color configs will no longer be respected, but `log.changeset` and `log.desc` will be respected instead. Differential Revision: https://phab.mercurial-scm.org/D9254

rebase: change and standarize template for rebase's one-line summary This removes the default template in rebase and switches to a centrally defined template. I've simplified it a bit to avoid the conditional parenthesis. I've also added labels so the different parts can be easily colored. The template is somewhat similar to what we've used internally at Google for a few years. I'm happy to change the template if others have opinions. Should we reuse the `color.log.` names as I have? Differential Revision: https://phab.mercurial-scm.org/D9252

rebase: make summary template configurable, with default to shared template Differential Revision: https://phab.mercurial-scm.org/D9251

rebase: use hard-coded template for one-line commit description This is to prepare for making making the one-line summary customizable. The template ended up pretty complicated because of the conditional output of "(<bookmarks etc>)". Maybe we can simplify the template later. Differential Revision: https://phab.mercurial-scm.org/D9250

config: move ui.pre-merge-tool-output-template into [command-templates] Differential Revision: https://phab.mercurial-scm.org/D9249

config: rename ui.mergemarkertemplate to command-templates.mergemarker Differential Revision: https://phab.mercurial-scm.org/D9247

config: rename ui.graphnodetemplate to command-templates.graphnode Differential Revision: https://phab.mercurial-scm.org/D9246

config: add a new [command-templates] section for templates defined by hg The existing `[templates]` section lets the user define their own keys and then refer to them on the command line with `-T`. There are many cases where hg wants to use a user-defined template with a given name, such as `ui.logtemplate` and `ui.mergemarkertemplate`. This patch starts moving such configs in a common section by moving `ui.logtemplate` to `command-templates.log` (with an alias from the old name, of course). Differential Revision: https://phab.mercurial-scm.org/D9245

i18n: fix coding tag unsupported by xgettext Running `make update-pot` currently fails with the following error: xgettext: mercurial/metadata.py:1: Unknown encoding "utf8". Proceeding with ASCII instead. xgettext: Non-ASCII string at mercurial/metadata.py:311. Please specify the source encoding through --from-code or through a comment as specified in http://www.python.org/peps/pep-0263.html. Differential Revision: https://phab.mercurial-scm.org/D9260

py3: hggettext `itervalues()` is only available on Python 2. Since this script doesn't currently refer to the main Mercurial modules, and as a result doesn't have easy access to the `pycompat` module, I simply changed it to use `value()` instead. Although this allocates a list on Python 2, I'd consider that acceptable for a utility script; Mercurial doesn't have all _that_ many commands anyway. Differential Revision: https://phab.mercurial-scm.org/D9259

relnotes: copy "next" to "5.6" and clear "next" The same procedure as every year^Wcycle. Differential Revision: https://phab.mercurial-scm.org/D9263

repoview: only pin obsolete wdir parents while there are unresolved conflicts I noticed after doing an update from an obsolete revision with a dirty wdir that the obsolete commit stayed visible for no obvious reason. It was decided in 85b03b1e4715 not to clear mergestate once all of the conflicts were resolved, in order to allow re-resolving. Since the point of pinning the obsolete parents was to allow resolving in the first place (aaeccdb6e654), it makes sense to also gate it on whether or not there are any remaining files to resolve. This might result in pinning again if files are marked unresolved again, but that seems reasonable, given that it still solves the original issue. Note that this isn't purely cosmetic- pushing with a pinned obsolete revision is likely to cause complaints about pushing multiple heads or other unexpected errors. So the faster it comes out of that state, the better. Differential Revision: https://phab.mercurial-scm.org/D9248

backout: don't assume that tip as what we just committed Differential Revision: https://phab.mercurial-scm.org/D9256

url: do not continue HTTP authentication with user=None (issue6425) I initially thought this is a py3-compat bug of passwordmgr._writedebug(), but actually returning (None, str) pair is wrong at all. HTTP authentication would continue with user="None" in that case. Since registering a password of user=None should also be wrong, this patch simply adds early return.

ui: fix echo back of ui.prompt() to not concatenate None as bytes Spotted while writing tests for the issue6425. The default value may be None.

commit: don't change phases for preexisting commits I noticed when pulling with hg-git in a repository that already had the changes, but pulled from another Mercurial repository. This meant that hg-git would re-create exact matches of the changesets, and if they were public, they'd get reverted to drafts. Differential Revision: https://phab.mercurial-scm.org/D9253

branching: merge with stable

demandimport: don't raise AttributeError if `exec_module` is missing I assume this was meant to do the check gracefully. After shoveling a bunch of modules into the ignore list in order to get keyring to work out of the box on CentOS 8, I hit the following error accessing the password, which the change fixes. Now the SecretStorage backend works out of the box, without any edits to the ignore list. ** Unknown exception encountered with possibly-broken third-party extension mercurial_keyring ** which supports versions unknown of Mercurial. ** Please disable mercurial_keyring and try your action again. ** If that fixes the bug please report it to https://foss.heptapod.net/mercurial/mercurial_keyring/issues ** Python 3.6.8 (default, Apr 16 2020, 01:36:27) [GCC 8.3.1 20191121 (Red Hat 8.3.1-5)] ** Mercurial Distributed SCM (version 5.5.2) ** Extensions loaded: evolve, topic, rebase, absorb, mercurial_keyring Traceback (most recent call last): File "/home/mharbison/hg_py3.6.8_venv/lib64/python3.6/site-packages/mercurial_keyring.py", line 230, in _read_password_from_keyring password = keyring.get_password(KEYRING_SERVICE, pwdkey) File "/home/mharbison/hg_py3.6.8_venv/lib64/python3.6/site-packages/keyring/core.py", line 53, in get_password return _keyring_backend.get_password(service_name, username) File "/home/mharbison/hg_py3.6.8_venv/lib64/python3.6/site-packages/keyring/backends/chainer.py", line 51, in get_password password = keyring.get_password(service, username) File "/home/mharbison/hg_py3.6.8_venv/lib64/python3.6/site-packages/keyring/backends/SecretService.py", line 79, in get_password return item.get_secret().decode('utf-8') File "/home/mharbison/hg_py3.6.8_venv/lib64/python3.6/site-packages/secretstorage/item.py", line 105, in get_secret decryptor = Cipher(aes, modes.CBC(aes_iv), default_backend()).decryptor() File "/home/mharbison/hg_py3.6.8_venv/lib64/python3.6/site-packages/cryptography/hazmat/backends/__init__.py", line 15, in default_backend from cryptography.hazmat.backends.openssl.backend import backend File "<frozen importlib._bootstrap>", line 971, in _find_and_load File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked File "<frozen importlib._bootstrap>", line 665, in _load_unlocked File "/home/mharbison/hg_py3.6.8_venv/lib64/python3.6/site-packages/hgdemandimport/demandimportpy3.py", line 53, in exec_module self.loader.exec_module(module) File "/home/mharbison/hg_py3.6.8_venv/lib64/python3.6/site-packages/cryptography/hazmat/backends/openssl/__init__.py", line 7, in <module> from cryptography.hazmat.backends.openssl.backend import backend File "<frozen importlib._bootstrap>", line 971, in _find_and_load File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked File "<frozen importlib._bootstrap>", line 665, in _load_unlocked File "/home/mharbison/hg_py3.6.8_venv/lib64/python3.6/site-packages/hgdemandimport/demandimportpy3.py", line 53, in exec_module self.loader.exec_module(module) File "/home/mharbison/hg_py3.6.8_venv/lib64/python3.6/site-packages/cryptography/hazmat/backends/openssl/backend.py", line 14, in <module> from six.moves import range File "<frozen importlib._bootstrap>", line 971, in _find_and_load File "<frozen importlib._bootstrap>", line 951, in _find_and_load_unlocked File "<frozen importlib._bootstrap>", line 894, in _find_spec File "/home/mharbison/hg_py3.6.8_venv/lib64/python3.6/site-packages/hgdemandimport/demandimportpy3.py", line 117, in find_spec and getattr(spec.loader, "exec_module") AttributeError: '_SixMetaPathImporter' object has no attribute 'exec_module' Differential Revision: https://phab.mercurial-scm.org/D9243

test: avoid bashisms in test-transaction-rollback-on-sigpipe.t Differential Revision: https://phab.mercurial-scm.org/D9239

automation: upload Python 3.9 Windows wheels We are producing these. We should be publishing them.

contrib: split Windows requirements into multiple files Package support for Python 2 has diverged significantly. It is no longer trivial to maintain a single requirements file that supports both Python 2 and 3 because the set of packages and versions varies wildly. This commit split up the Windows requirements files so we have variants for Python 2 and 3. As part of this, I also renamed the files to have what I believe to be more reasonable naming ("win32" felt like a weird identifier to me). We can see that some package versions decreated on 2.7. This is because the old pinned versions weren't compatible with Python 2.

relnotes: add diffcontains() to new features list

revset: rename diff(pattern) to diffcontains(pattern) Suggested by Augie, and I think it's better name.

pyoxidizer: update to PyOxidizer 0.9 We were previously using a Git commit from a few days before the 0.8 release. This commit upgrades us to the just-released 0.9 release. This required some Starlark changes due to backwards incompatible changes. Differential Revision: https://phab.mercurial-scm.org/D9228

Added signature for changeset 0e06a7ab9e0d

Added tag 5.6rc0 for changeset 0e06a7ab9e0d

merge with default for 5.6rc0

tag: leverage cmdutil.check_incompatible_arguments() Differential Revision: https://phab.mercurial-scm.org/D9223

serve: leverage cmdutil.check_incompatible_arguments() Differential Revision: https://phab.mercurial-scm.org/D9222

revert: leverage cmdutil.check_incompatible_arguments() Differential Revision: https://phab.mercurial-scm.org/D9221

incoming: leverage cmdutil.check_incompatible_arguments() Differential Revision: https://phab.mercurial-scm.org/D9220

grep: levarage cmdutil.check_incompatible_arguments() Differential Revision: https://phab.mercurial-scm.org/D9219

import: leverage cmdutil.check_incompatible_arguments() Differential Revision: https://phab.mercurial-scm.org/D9217

backout: leverage cmdutil.check_incompatible_arguments() Differential Revision: https://phab.mercurial-scm.org/D9216

transaction: use ProgrammingError for when an committed transaction is used It seems to me that ProgrammingError is the right type of error here. Differential Revision: https://phab.mercurial-scm.org/D9215

hook: ignore EPIPE when flushing stdout/stderr This fixes the bug described in the parent commit. test-transaction-rollback-on-sigpipe.t is updated to show the new behavior. Differential Revision: https://phab.mercurial-scm.org/D9152

test: add test-transaction-rollback-on-sigpipe.t demonstrating py3 regression When an hg push is interrupted with C-c, the remote [hg serve] command receives SIGPIPE. If a pretxnchangegroup hook fails, the remote hg then tries to rollback the transaction. It begins by printing "transaction abort!\n". This returns EPIPE, but ui.py ignores that error. In python3 (but not python2), this "transaction abort!\n" message stays in a buffer, so future flushes of stderr will try to print the message again, and so those flushes will also hit EPIPE. This test demonstrates such a case where this EPIPE causes the transaction rollback to fail, leaving behind an abandoned transaction. Differential Revision: https://phab.mercurial-scm.org/D9151

upgrade: allow sidedata upgrade to modify revision flag In the process, we fix the lack of HAS_COPIES_INFO flag on upgrade, and test the results. Differential Revision: https://phab.mercurial-scm.org/D9199

sidedata: return enough data to set the proper flag in the future If the revision has information relevant to copy tracing, we need to set a dedicated flag in revlog. Currently the upgrade process is failing to do so. Before we teach the upgrade process about flags, we make the information available where we will needs it. Differential Revision: https://phab.mercurial-scm.org/D9198

test: move upgrade run and check earlier in test-copies-chain-merge We are about to introduce an explicit case for copy tracing after a upgrade. So I am moving the code around beforehand for clarity. Differential Revision: https://phab.mercurial-scm.org/D9196

copies: split creation of the graph and actual checking again The re-install the old split. It will be necessary to test that the upgrade process produced a functionally identical result. It will be useful to detect case where the metadata we look at identical, but some other items we did not checked are missing. (spoiler: we will find some bug) Differential Revision: https://phab.mercurial-scm.org/D9195

copy: clarify in help text that `hg co --forget` takes a *destination* file We had a user who tried to pass a source file. The command then fails with `<file>: not unmarking as copy - file is not marked as copied`, so at least it's not just silent, but let's be a little clearer in the documentation. Differential Revision: https://phab.mercurial-scm.org/D9214

test: check server error output in `test-pull-bundle.t` This is useful to debug test failure when they happens. Differential Revision: https://phab.mercurial-scm.org/D9213

unbundle: free temporary objects after use This reduces peak RSS for larger unbundle operations by ~30 Bytes per changeset on AMD64. This can't be a direct delete for Python 2.7, so reset the object instead and leave a comment. The efilesset object can't be deleted as it is referenced by the local onchangelog function and Python 2.7 rejects a delete on the existance of a nested scope. Differential Revision: https://phab.mercurial-scm.org/D9153

changing-files: add a shorthand property to check for copy relevant info We are going to reuse this change in more place, so we factor it out first. Differential Revision: https://phab.mercurial-scm.org/D9197

pycompat: add an entry for unnamedtmpfile I am going to use unnamed temporary files to pass arbitrarily large input data to worker creating bundles. To do so, I need a unified API that work on py2 and py3. Differential Revision: https://phab.mercurial-scm.org/D9211

pycompat: update comment about unnamedtempfile I found the comment clearer. I end up having to think about this for `TemporaryFile` and I update that one in the process. Differential Revision: https://phab.mercurial-scm.org/D9210

revset: add diff(pattern) predicate for "grep --diff" I find this is useful in GUI log viewer since the tool only needs to support "log -rREV" command. This is basic implementation. Windowed search is not implemented since it wouldn't work pretty well with the smartset API. And filename matcher is not supported because the syntax isn't determined. My idea is to add handling of diff(pattern, file(..)) and diff(pattern, follow(..)), which will then be evolved to a full revset+matcher combinator support: x & diff(pattern, y & z) ===== y & z builds (revs(y) & revs(z), matcher(y) & matcher(z)) pair, and narrows the search space of diff() ==================== diff() returns matched (revs, matcher) pair ======================== revs and matcher will be combined respectively by &-operator, and the matcher will optionally be used to filter "hg log -p" output The predicate name "diff()" wouldn't be great, but grep() is already used. Another options I can think of are "grepdiff()" and "containsdiff()". Naming suggestions are welcome.

stringutil: add function to compile stringmatcher pattern into regexp Prepares for adding a revset predicate for "grep --diff". The grep logic needs a regexp object instead of a match function.

py3: fix stringmatcher() to byte-stringify exception message Spotted while writing regexp variant of stringmatcher().

stringutil: extract helper function that splits stringmatcher() pattern

grep: extract main search loop as searcher method Still displayer part is in commands.grep(), the core grep logic is now reusable. I'll revisit the displayer stuff later since it will be another long series.

scmutil: move walkchangerevs() from cmdutil It's no longer a command-level function, but a pure helper to walk revisions in a windowed way. This change will help eliminate reverse dependency of revset.py -> grep.py -> cmdutil.py in future patches.

grep: extract public function to register file to be skipped The main grep loop will be extracted to a searcher method, but this skipping condition depends on the result of display() function.

posix: avoid a leaked file descriptor in a unix domain socket exception case Differential Revision: https://phab.mercurial-scm.org/D9206

posix: use context managers in a couple of places Differential Revision: https://phab.mercurial-scm.org/D9205

record: when backing up, avoid generating very long filenames If the original file's path is longer than the individual filename maximum length (256 on Linux, I believe?), then this mechanism of "replace slashes with underscores" causes an error. Now, we'll produce just the "basename" of the file, plus some stuff to ensure it's unique. This can be potentially confusing for users if there's a file with the same name in multiple directories, but I suspect that this is better than just breaking. Example: `<reporoot>/a/long/path/to/somefile.txt` used to be backed up as `<reporoot>/.hg/record-backups/a_long_path_to_somefile.txt.abcdefgh`, it will now be backed up as `<reporoot>/.hg/record-backups/somefile.txt.abcdefgh` We could do the naive thing (what we were doing before) and have it to doing something with either subdirectories (`<backuproot>/a/long/path/to/somefile.txt.abcdefgh` or minimize #dirs with `<backuproot>/a_long_path/to_somefile.txt.abcdefgh`), prefix-truncated paths (such as `<backuproot>/__ath_to_somefile.txt.abcdefgh`, where that `__` elides enough to get us under 255 chars (counting the +9 we need to add!)), or hash-of-dirname (`<backuproot>/<sha1sum_of_dirname>/somefile.txt.abcdefgh`), but ultimately every option felt over engineered and that it would be more likely to cause problems than it would be to solve any, especially if it was conditional on directory length. Differential Revision: https://phab.mercurial-scm.org/D9207

mergestate: add `allextras()` to get all extras `extras()` can only be used for getting extra for a file. However at couple of places in code, we wanted to iterate over all the extras stored with the mergestate and they were accessing the private `_stateextras`. We add a new function for this. Differential Revision: https://phab.mercurial-scm.org/D9190

mergestate: document `o` merge record state in _mergestate_base docs _mergestate_base documentation serves as a nice documentation for mergestate. This also documents known merge records and known merge record states. I missed adding `o` state to it when I introduced it. Let's add it now. Differential Revision: https://phab.mercurial-scm.org/D9156

fix: update commit hash references in the new commits Differential Revision: https://phab.mercurial-scm.org/D9183

absorb: update commit hash references in the new commits Differential Revision: https://phab.mercurial-scm.org/D9182

rewriteutil: handle dropped commits when updating description hashes In looking to leverage this with the absorb extension, the old -> new mapping there allows the new value to be None. We could filter that out and not pass it to this method, but it seems worth a message to the user. (I wonder if these should be an info or warning, because it's unlikely people are using `-v` regularly.) Differential Revision: https://phab.mercurial-scm.org/D9181

dirstate-tree: move a conditional in an explicit boolean This will help readability a bit and make the next change simpler to read. Differential Revision: https://phab.mercurial-scm.org/D9202

rust: cleanup some white space in a dock They seems to have sneaked there somehow. Differential Revision: https://phab.mercurial-scm.org/D9201

commit: pass ChangingFiles object as argument to _process_files Instead of returning it, we pass it as an argument. This makes the whole if-else in `_prepare_files` a bit simpler. Else each if-else branch was creating the object. Differential Revision: https://phab.mercurial-scm.org/D9194

commit: pass mergestate into `_process_files` instead of re-reading it Differential Revision: https://phab.mercurial-scm.org/D9193

commit: move salvaged calculation a bit earlier in the function This helps us initialize mergestate before and now we can pass it into `_process_files()` instead of re-reading it there. Differential Revision: https://phab.mercurial-scm.org/D9192

commit: refactor salvage calculation to a different function Differential Revision: https://phab.mercurial-scm.org/D9191

tests: run test-copies-chain-merge.t also with copies in changesets We have these tests already and it seems like a waste to not run them in the changesets case. The biggest differences stem from `hg log --follow` not working with copies stored in the changeset extras. Differential Revision: https://phab.mercurial-scm.org/D9173

tests: add test of copies suggested by Pierre-Yves on D9159 Differential Revision: https://phab.mercurial-scm.org/D9171

tests: update test-copies-chain-merge.t to not use empty files Merging empty files is not very interesting or realistic. Differential Revision: https://phab.mercurial-scm.org/D9172

revset: fix sorting key of wdir revision It would go wrong on Python 2, and would crash on Python 3.

grep: move prep() to grepsearcher class

grep: move readfile() to grepsearcher class

grep: move getbody() to grepsearcher class

grep: add stub class that maintains cache and states of grep operation Prepares for extracting stateful functions from commands.grep().

grep: move match and diff logic to new module commands.grep() has lots of functions and classes. Let's split it into reusable components so we can leverage them to implement a revset predicate for 'hg grep --diff'. I want to do 'hg log -r "diff(pattern)"'.