Add symmetric merge tests for some more of the planned cherry-pick scenarios.
Add symmetric merge tests for some more of the planned cherry-pick scenarios.

* subversion/tests/cmdline/merge_symmetric_tests.py
  (get_mergeinfo_change): Fix a bug in parsing the mergeinfo diff: it was
    not picking up multiple ranges separated by a comma.
  (expected_symmetric_merge_output): Allow a 'Recording mergeinfo'
    notification line to contain any pair of end revision numbers.
  (cherry1_fwd, cherry3_fwd): New tests.
  (test_list): Add the new tests.

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