Follow-up to r35338, add some more explanation to an XFailing merge test.
Follow-up to r35338, add some more explanation to an XFailing merge test.

Suggested by: gstein

* subversion/tests/cmdline/merge_tests.py
  (merge_dir_and_file_replace): Add a comment to this test for issue #2690
  regarding where and how we expect this test to fail.  Prior to r35338 this
  was actually failing in the test setup for tree conflict reasons and we
  weren't actually testing the issue in question.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@875445 13f79535-47bb-0310-9956-ffa450edef68

wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion