tests/test-username-newline.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

  ...

  $ hg init
  $ touch a

  $ unset HGUSER
  $ echo "[ui]" >> .hg/hgrc
  $ echo "username= foo" >> .hg/hgrc
  $ echo "          bar1" >> .hg/hgrc

  $ hg ci -Am m
  adding a
  abort: username 'foo\nbar1' contains a newline
  
  [255]
  $ rm .hg/hgrc

  $ HGUSER=`(echo foo; echo bar2)` hg ci -Am m
  abort: username 'foo\nbar2' contains a newline
  
  [255]
  $ hg ci -Am m -u "`(echo foo; echo bar3)`"
  transaction abort!
  rollback completed
  abort: username 'foo\nbar3' contains a newline!
  [255]