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.

test-hardlink: stop explicitly listing `undo.dirstate` The files is on its way out.

localrepo: enforce a clean dirstate when the transaction open This is important to simplify the backup process. This also seems like a quite reasonable expectation. See inline documentation for details.

dirstate: explicitly backup the datafile Since the transaction does not know about this file, we need to explicitly mark it for backup before touching it.

mq: write the dirstate before stripping I am not certain why it is dirty (probably the `repo.setparent` call a right before. However I know we need it flushed before the repository starts to be stripped.

dirstate: simplify the shelve hack to not go through the disk We already have the data in memory, so why not simply keep the data in memory? This avoid abusing the `savebackup/restorebackup` logic and will make our life easier.

dirstate: detect potential fishy transaction patterns while changing If we rely on the transaction more, we should be more careful about the transaction. Adding extra security seems reasonable.

dirstate: generalize the dirstate's invalidation on transaction abort The previous code was too specific, we should add the invalidation at next to the `addfilegenerator` in the `write` call.

dirstate: simplify some methods' decorator Since `changing_parents` and `changing_files` are mutually exclusive, having both `@requires_changing_files` and `@requires_not_changing_parents` on a method is redundant.

dirstate: document the functions that need consolidation They are more functions that make the dirstate dirty but does not currently enforce a clean change scoping, we add comments in front of each of them so clarify this. There is no urgency to it, but the world will be a better place when all of them have proper scoping in place.

dirstate: make `restorebackup` more robust when it is a noop If there are no data_file, we might not be able to determine its filename. Which can be safely ignored. (all this code is on the way out anyway)

dirstate-guard: remove the feature The dirstate guard duplicated some of the logic already implemented in the transaction (and now the changing_* context). However the feature was incomplete, for example, living only in memory meant we could not recover from the hardest crash. In addition this duplicated with the transaction logic meant things could go out of sync or step on each other. Removing the feature now that we no longer needs it seems the safest.

rollback: remove the dirstateguard usage Thanks to the previous changeset, we no longer needs it. begone !

rollback: explicitly skip dirstate rollback when applicable instead of letting the transaction logic overwrite the dirstate and then overwrite that overwrite with a backup. We simply do not restore the dirstate related file during the _playback call. This open the way to removing the last dirstate guard usage.

rollback: detect "parentgone" case earlier Detecting this earlier will help us to affect the rollback process sooner, which will help the next changesets. To keep things simple, we degrade the behavior a bit when the `undo.desc` is missing. However since `hg rollback` is not supposed to be used and the `undo.desc` file have been introduced in mercurial 1.6 (2010). I think this is an acceptable evil.

rollback: avoid a `hg commit --addremove` at a critical point The rollback behavior around `hg commit --addremove` has changed slightly. It does not really matters here but keeping that variant out of the way cannot hurt.

rollback: display some graphlog before/after a test piece This make the situation clearer.

rollback: show that the safety works in a associated test That test section is checking that --force is overcoming the safety check, however we did not check that the safety properly detect the situation. We now do for clarity.

dirstate-guard: remove its usage in `backout` We can simply replace it with a transaction.