obsolete: refuse to push divergent changeset
As other troubles `unstable` and `bumped`. Followup patches may simplify the
push code with unification of "obsolescence troubles" handling.
$ "$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)