dirstate: use the new `check_invalidated` decorator for `_changing` WeeeEEeee, less code.

dirstate: introduce a check_invalidated decorator This is a common need, so let us consolidate it to simplify the code.

dirstate: warn if dirty when starting an edition The dirstate should be clean before we start changing it. Otherwise we might write unrelated changes. Having a dirty dirstate laying around is also suspicious. This is similar to what we do when opening a new transaction, but this time this affect dirstate changes outside of a transaction.

large-files: make sure we write newly initialized standin file early Any changing context will have to initialized it before anything else. Not flushing the default (pre-change) content mean we would enter the changing context with a dirty dirstate, which is odd.

dirstate: mark `clear` and `rebuild` as `require_changing_parents` Yeah, more scoping!

dirstate: add a comment about the semantic of `dirstate.clear` This method is weird, lets flag it as such.

debugrebuildstate: wrap the operation in a `changing_parents` context This ismaybe a "changing_files" case? However this would be the only usage of `rebuild` outside a `changing_parents` context and this is a debug command, so lets not make the code base more complex because of that one command.

strip: use a `changing_parents` context for --keep update These are now properly scoped. note: it would be neat to reuse this in `hg rollback`.

mq: wrap the dirstate's rebuild in a `changing_parents` context This code is dealing with `qreshesh` failure. In that case the working copy will be left on the parent of the refreshed patch, so the parents are changing and `changing_parents` make sens.

lfconvert: use a `changing_parents` context to clear the dirstate Not sure if this is the right context, but it works and it is consistent with the other usages of `dirstate.clear`.

dirstate: mark the `copy` method as requiring a `changing_any` context This is used both when changing parents (e.g. merging with rename) and changing files (e.g. running `hg rename`).

dirstate: add a `require_changing_any` decorator We will need it for a couple of usecase (e.g `dirstate.copy`).

rebase: scope parent change into a changing_parents context If we are actually altering the working copy (i.e. we are not in memory), we should properly scope the working copy update.

dirstate: requires being in a `changing_parents` `context to set_parents` Enforcing proper operation scoping on all methods that mutate the dirstate will tighten correctness and reduce the risk of bugs. The context to use for this method is obvious, and all code was already compliant ☺

dirstate: invalidate on all exceptions Previously, we would miss SystemExit, KeyboardInterrupt etc. This "fix" on the bug tested in "test-largefiles-update.t" by preventing the precisely tested situation to happens at all. However this reveal a similar bug with a different timing. I have not been able to deal with that pre-existing bug so far. So I updated the test to point that out.

large-files: prepare a test for more changes The behavior around this test is about to change. We update the test to make it more robust and the changes clearer.

large-files: larger "changing_parents" context in mergeupdate override This since we are updating the lfdirstate early, it seems reasonable to include the full function in that scope.

large-files: use `hacky_extension_update_file` one more time This override is about merging and can be used in a `changing_parents` context. So lets use the method dedicated to hacky stuff when doing hacky stuff.

typing: disable `signature-mismatch` warnings on a few bytestr functions Recent versions of pytype complain about this, but it seems like expected behavior.

branching: merge with stable

rhg: fix a bug in path_encode This makes rhg able to access long paths at the root of the tree just fine.

rhg: demonstrate a bug in path_encode The bug means that long filenames at the root of the tree are encoded incorrectly by rhg, so rhg crashes when trying to access them.

rhg: nicer error message

typing: add type hints to argument checking functions in cmdutil These might be surprising, since they can take strings instead of bytes. The way `AnyStr` works is that it must be all bytes or all str for any given invocation. The wildcard here will be the `opts` that get passed in- if the type is unknown and defaults to `Any`, there's no enforcement that the dict key type matches the additional args. But a lot of uses should be using `**opts` from the command method, which has a str key. The uses of these methods in this module are now typed because their internals force a specific type, and it can't just be inferred from the caller.

tag: move the prohibition of tagging the `null` rev up to the `wdir()` check It makes sense to do these together, and avoid another revision lookup.

branching: merge with default the first part of the fix is there

tests: remove unnecessary --traceback argument

dirstate: remove the dedicated backup logic When alone, the dirstate can now take care of its commit/rollback pattern itself. When in a transaction, the transaction deal with commit/rollback pattern quite fine. Why did you have a dedicated backup logic?

localrepo: stop doing special dirstate backup at transaction open Since the dirstate writes are already managed by the transaction, we already do a backup of the dirstate when necessary (and even trigger one to keep `hg rollback` happy). We needs some special code to deal with the initial empty checkout, but it is not too complicated. Managing variable filename (as dirstate-v2 uses) at the "journalfile" level, is complex and fragile (which is consistent with the fact these files are not journal…). If we no longer do it, our life is significantly simpler. In some sense, we apply the xkcd-1134¹ solution to our savebackup/restorebackup problem. [1] https://xkcd.com/1134/ (the change to test-hardlink are expect as decreasing the number of duplicated backup drive the hardlink count down)

localrepo: "blindly" do a dirstate backup at the end of the transaction Having the file backup mechanism dealing with file backup as benefit. So lets move closer to that. The fact `hg rollback` even needs this is sad. I hope to have the time to implement one of the alternative soon.