merge with stable

share: do not write working-copy requirements twice Follows up d252f51ab032. Maybe it is a copy-paste error.

py3: fix formatting of LookupError for workingctx Spotted while writing broken tests for "hg grep -fr'wdir()'". basectx._fileinfo() raises ManifestLookupError(self._node, ..), but _node of the workingctx is None for historical reasons.

phabricator: fix loadhgrc() override broken by D8656 This fixes some failing `test-check*` tests (at least `test-check-code.t` was broken). Differential Revision: https://phab.mercurial-scm.org/D9044

mergestate: move commit() from base class to on-disk subclass The commit message doesn't do anything in the in-memory case, and it's `_makerecords()` is also not needed in that case, so let's move it down to the on-disk subclass (i.e. the `mergestate` class). Sorry I missed this earlier. Differential Revision: https://phab.mercurial-scm.org/D9043

mergestate: make in-memory mergestate not clear on-disk mergestate on reset() Oops, I thought I had remove the `rmtree()` call earlier. Maybe I accidentally got it back in a histedit or something. Differential Revision: https://phab.mercurial-scm.org/D9042

merge: use in-memory mergestate when using in-memory context This is my version of Augie's D8568. It makes it so we don't touch the mergestate on disk when using an in-memory context. The reason that I want this is not the same as the reason that Augie write his patch (though I agree with that reason too). My hope is to make in-memory rebase not fall back to on-disk rebase when there are conflict. I plan to do that by adding a `overlayworkingctx.reflect_in_workingcopy()`. The idea is that that will update the working copy, the dirstate and the mergestate as necessary. Differential Revision: https://phab.mercurial-scm.org/D9040

mergestate: extract a base class to be shared by future memmergestate This extracts a new base class from `mergestate` and leaves all the vfs-touching code in `mergestate`. Differential Revision: https://phab.mercurial-scm.org/D9039

mergestate: extract overridable methods for making/restoring file backups In-memory merge currently still uses on-disk mergestate. That's mostly harmless (I don't think I've seen any problem it's actually caused). It's still a little weird. I'm planning to add an in-memory mergestate, which will be used with `overlayworkingctx`. This patch prepares for that by extracting that logic, so it's easier to change per subclass. Differential Revision: https://phab.mercurial-scm.org/D9038

mergestate: initialize all properties in __init__() This is hopefully not very controverial. I found the initialization before this patch unorthodox. It wasn't clear which properties the object was supposed to have. Differential Revision: https://phab.mercurial-scm.org/D9037