typing: disable a few errors calling py3.7+ functions in resourceutil.py There's a graceful fallback when these methods are unavailable. Differential Revision: https://phab.mercurial-scm.org/D10205

test-copies: add a test updating file content while merging a pure overwrite As the current test misbehavior show, this confuse various part of the code: - the committed file is different depending of the commit source, - the upgrade code compute the wrong information on this changeset. This will be fixed in upcoming patches. Differential Revision: https://phab.mercurial-scm.org/D10087

mergestate: don't pop stateextras when there are no conflicts on filemerge Even if `filemerge.filemerge()` didn't result in conflicts, we should not remove stateextras for a file since we now use that for more things than just merge time information. We use stateextras to store information which is required to be used by commit. I tracked this down while finding why a patch of mine which adds more commit related information does not work as expected and looses the extras in mergestate. Differential Revision: https://phab.mercurial-scm.org/D10148