Expand test coverage for issue #4138 'replacement in merge source not
notified correctly'.

* subversion/tests/cmdline/merge_tests.py
  (merge_source_with_replacement): Check the resulting mergeinfo in addition
   to the merge notifications.  The notifications are still wrong (a minor
   problem) but the mergeinfo is wrong now too -- see
   http://subversion.tigris.org/issues/show_bug.cgi?id=4138#desc4


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1442785 13f79535-47bb-0310-9956-ffa450edef68