A follow-up to r23170, *correctly* improving the documentation for blackbox merge tests.
A follow-up to r23170, *correctly* improving the documentation for
blackbox merge tests.

* subversion/tests/cmdline/merge_tests.py
  (setup_dir_replace, merge_dir_replace): Improve/correct doc string
   for setup_dir_replace(), and inline comments for both.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@863247 13f79535-47bb-0310-9956-ffa450edef68

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