filemerge: move check for identical sides out of filemerge()
`filemerge.filemerge()` returns `None` if no merge was necessary
because the two sides were identical. I don't think it should be that
function's responsibility to handle that case; we should ideally not
even call `filemerge.filemerge()` if the two inputs identical. This
patch therefore moves the check out to the caller (`mergestate.py`).
The largefiles test changed because we now notice that the two sides
made the same change, so we don't consider it a merge. Also note that
the new message better matches the line above it in the test output.
Differential Revision: https://phab.mercurial-scm.org/D12154
$ hg init
$ echo a > a
$ hg ci -Am0
adding a
$ hg -q clone . foo
$ touch .hg/store/journal
$ echo foo > a
$ hg ci -Am0
abort: abandoned transaction found
(run 'hg recover' to clean up transaction)
[255]
$ hg recover
rolling back interrupted transaction
(verify step skipped, run `hg verify` to check your repository content)
recover, explicit verify
$ touch .hg/store/journal
$ hg ci -Am0
abort: abandoned transaction found
(run 'hg recover' to clean up transaction)
[255]
$ hg recover --verify
rolling back interrupted transaction
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 1 changesets with 1 changes to 1 files
recover, no verify
$ touch .hg/store/journal
$ hg ci -Am0
abort: abandoned transaction found
(run 'hg recover' to clean up transaction)
[255]
$ hg recover --no-verify
rolling back interrupted transaction
(verify step skipped, run `hg verify` to check your repository content)
Check that zero-size journals are correctly aborted:
#if unix-permissions no-root
$ hg bundle -qa repo.hg
$ chmod -w foo/.hg/store/00changelog.i
$ hg -R foo unbundle repo.hg
adding changesets
abort: Permission denied: '$TESTTMP/foo/.hg/store/.00changelog.i-*' (glob)
[255]
$ if test -f foo/.hg/store/journal; then echo 'journal exists :-('; fi
#endif