obshistory: use successorsandmarkers() from obsutil, drop local variant
It's been in core since 4.4 and is identical to the version removed by this
patch, except it returns None if ctx is not obsolete.
$ cat >> $HGRCPATH <<EOF
> [extensions]
> EOF
$ echo "evolve=$(echo $(dirname $TESTDIR))/hgext3rd/evolve/" >> $HGRCPATH
Test outputting version number
$ hg version -v
Mercurial Distributed SCM (version *) (glob)
(see https://mercurial-scm.org for more information)
Copyright (C) 2005-* Matt Mackall and others (glob)
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Enabled extensions:
evolve external * (glob)
Test install
TODO: fix warning
$ "$PYTHON" "$TESTDIR/../setup.py" install --root "$TESTTMP/installtest" > /dev/null
*/distutils/dist.py:*: UserWarning: Unknown distribution option: 'python_requires' (glob)
warnings.warn(msg)