tests: allow [Errno] in output
I'm not sure why, but my system is printing "[Errno -5]" before
the "No address associated with hostname" message. I suspect a
modern version of Python improved errno tracking or something.
Add an "[Errno ...]" pattern as optional output to make the test
pass.
Differential Revision: https://phab.mercurial-scm.org/D1958
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init
$ echo 'base' > base
$ hg ci -Ambase
adding base
$ hg qnew -mmqbase mqbase
$ hg qsave
$ hg qrestore 2
restoring status: hg patches saved state