manifestmerge: handle abort on local unknown, remote created files
This replaces the _checkunknown call in calculateupdates with a more
performant version. On a repository with over 150,000 files, this speeds up an
update by 0.6-0.8 seconds, which is up to 25%.
This does not introduce any UI changes. There is existing test coverage for
every case, mostly in test-merge*.t.
$ "$TESTDIR/hghave" pyflakes || exit 80
$ cd "`dirname "$TESTDIR"`"
$ pyflakes mercurial hgext 2>&1 | "$TESTDIR/filterpyflakes.py"
hgext/inotify/linux/__init__.py:*: 'from _inotify import *' used; unable to detect undefined names (glob)