evolve: Changelog

evolve: check that relocating makes sense in _solvedivergent() (issue5958)

tests: demonstrate content divergence causing "relocate node on top of itself"

cmdstate: introduce a "saver" contextmanager and use it in place of save() Previously, the state was only saved in some paths out of these functions. This can be problematic, if the user ctrl-c's (or `kill -9`'s) the process, or we exit out of `relocate` for anything besides the "expected" reason, we won't record that we were in the middle of an evolve. One of our users has discovered that this leaves hg in a weird state; the user did something like this: ``` $ hg evolve <something goes wrong with the merge tool, hits ctrl-c> <deals with the merge conflicts> $ hg evolve --continue abort: no interrupted evolve to continue $ hg evolve abort: uncommitted changes # Note: commands.status.verbose=True is set. $ hg status M foo # The repository is in an unfinished *update* state. # No unresolved merge conflicts # To continue: hg update ``` The user did an `hg update`, but it didn't actually do anything besides take it out of the unfinished update state (the files were still dirty in the working directory).

cmdstate: avoid setting a default argument to a mutable object (`{}`) If there's ever more than one cmdstate for the lifetime of the process, this can cause surprising behavior where the later cmdstates pick up options from the earlier ones. I've not seen any evidence this is actually causing any issues, but it's subtle enough that it should probably be fixed to help save significant debugging time later.

cmdstate: switch to new-style classes This isn't a huge issue and isn't necessary on Python3, but we're still Python2 compatible and we should be consistent (and strongly prefer new-style classes); this is the only class that is not deriving from object that I could find.