cmdutil: stop tryimportone from using dirstateguard (BC) There is no user of 'cmdutil.tryimportone()' other than 'commands.import_()', which can restore dirstate at failure of applying patches by transaction or dirstateguard. Therefore, it is reasonable to stop 'tryimportone()' from using redundant 'dirstateguard', even though it changes behavior of 'tryimportone()'. After this patch, 3rd party extensions should use 'dirstateguard' or so explicitly, if they want to restore dirstate at failure of importing a patch.

dirstate: remove meaningless dirstateguard Previous patch made dirstate changes in a transaction scope "all or nothing". Therefore, 'dirstateguard' is meaningless, if its scope is as same as one of the related transaction. This patch removes such meaningless 'dirstateguard' usage.

localrepo: execute appropriate actions for dirstate at releasing transaction Before this patch, in-memory dirstate changes are still kept over a transaction scope boundary regardless of the result of it. For "all or nothing" policy of the transaction, in-memory dirstate changes should be: - written out at successful closing a transaction, because subsequent 'dirstate.invalidate()' can lose them - discarded at failure of a transaction, because outer 'wlock.release()' or so may write them out To discard all changes in a transaction completely, this patch also restores '.hg/dirstate' by '.hg/journal.dirstate' at failure, because 'transaction' itself does nothing for files related to '.hg/journal.*' in such case (therefore, renaming in this patch is safe enough). This is a part of preparations for "transactional dirstate". See also the wiki page below for detail about it. https://mercurial.selenic.com/wiki/DirstateTransactionPlan This patch also removes redundant 'dirstate.invalidate()' just before aborting a transaction for shelve/unshelve.

transaction: add releasefn to notify the end of a transaction scope 'releasefn' is used by subsequent patch, to do appropriate action according to the result of it at the end of a transaction scope. To ensure that 'releasefn' is invoked only once, this patch invokes it after assignment 'self.journal = None', because such assignment prevents from invoked 'transaction._abort()' again via '__del__()'. def __del__(self): if self.journal: self._abort()

filemerge: move post-merge checks into a separate function This makes the overall filemerge function easier to follow, and makes upcoming work simpler.

filemerge._xmerge: drop no longer necessary 'if r:' check Cleanup from an earlier patch to make premerge be directly called from the main filemerge function.

filemerge._idump: drop no longer necessary 'if r:' check Cleanup from an earlier patch to make premerge be directly called from the main filemerge function.

filemerge._merge: drop no longer necessary 'if r:' check Cleanup from an earlier patch to make premerge be directly called from the main filemerge function.

revset: delete _updatedefaultdest as it has no users The revset is not used anywhere anymore. We delete the function until we use (and therefore test it again).

merge: get the default update destination from the function There is no value in using the revset instead of the extracted function.