Follow-up to r16285: fix test failure over ra_dav.
Follow-up to r16285: fix test failure over ra_dav.

* subversion/tests/clients/cmdline/lock_tests.py
  (unlock_already_unlocked_files): Allow the error messages actually produced
  by ra_dav.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion