copy: to find copy source, walk parent of revision we're marking copies in
As shown in the previous patch, `hg cp --after --at-rev . src dst`
fails if `src` is not in `.`. It seems obvious that you should always
walk the *parent* of the revision you're marking copies in, but that's
not how it was done for the working copy, and I didn't think to change
it when marking copies in a non-working-copy commit.
This patch fixes that by walking the parent commit instead, but only
if we're marking copies for a non-working-copy commit. We need to
leave the working-copy code unchanged because it depends on the weird
behavior of `workingctx.walk()`. With these changes, there's very
little overlap between the working-copy version and the
non-working-copy version of `walkpats()`, but I've refrained from
cleaning that up on the stable branch.
Differential Revision: https://phab.mercurial-scm.org/D8494
# Files that just need to be migrated to the formatter.
# Do not add new files here!
mercurial/cext/manifest.c
mercurial/cext/osutil.c
# Vendored code that we should never format:
syntax: glob
contrib/python-zstandard/**.c
contrib/python-zstandard/**.h
hgext/fsmonitor/pywatchman/**.c
mercurial/thirdparty/**.c
mercurial/thirdparty/**.h