phases: apply similar early filtering to advanceboundary
advanceboundary is called the push's unbundle (but not the other unbundle) so
advanceboundary did not show up the profile I looked at so far.
We start with simple pre-filtering to avoid doing any work if we don't needs
too.
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init repo
$ cd repo
$ echo 'base' > base
$ hg ci -Ambase
adding base
$ hg qnew -mmqbase mqbase
$ hg qsave
$ hg qrestore 2
restoring status: hg patches saved state