tests/test-abort-checkin.t

manifest: set appropriate cache entry when clearing _dirlogcache()

manifestrevlog applies to any manifest, not just the root manifest.
Resetting the cache and populating its root entry with self is not
correct when the instance does not refer to the root manifest.

This has no test fallout. So I'm guessing we only ever call
clearcaches() on the root manifest. Or we have no test coverage that
are impacted by a bad cache on a non-root manifestrevlog.

Differential Revision: https://phab.mercurial-scm.org/D4275

  $ cat > abortcommit.py <<EOF
  > from mercurial import error
  > def hook(**args):
  >     raise error.Abort(b"no commits allowed")
  > def reposetup(ui, repo):
  >     repo.ui.setconfig(b"hooks", b"pretxncommit.nocommits", hook)
  > EOF
  $ abspath=`pwd`/abortcommit.py

  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > mq =
  > abortcommit = $abspath
  > EOF

  $ hg init foo
  $ cd foo
  $ echo foo > foo
  $ hg add foo

mq may keep a reference to the repository so __del__ will not be
called and .hg/journal.dirstate will not be deleted:

  $ hg ci -m foo
  error: pretxncommit.nocommits hook failed: no commits allowed
  transaction abort!
  rollback completed
  abort: no commits allowed
  [255]
  $ hg ci -m foo
  error: pretxncommit.nocommits hook failed: no commits allowed
  transaction abort!
  rollback completed
  abort: no commits allowed
  [255]

  $ cd ..