tests/test-mq-qsave.t

run-tests: use regex when searching for $HGPORT in test output

This prevents spurious errors when a changeset hash happens to match
the port number. Before, this invocation gave a test failure:

  $ ./run-tests.py test-log.t --port 24427
  ERROR: /home/mg/src/mercurial-crew/tests/test-log.t output changed
  --- /home/mg/src/mercurial-crew/tests/test-log.t
  +++ /home/mg/src/mercurial-crew/tests/test-log.t.err
  @@ -626,12 +626,12 @@

     $ hg log -b default
     changeset:   2:c3a4f03cc9a7
  -  parent:      0:24427303d56f
  +  parent:      0:$HGPORT303d56f
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     commit on default

  ...

  $ 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