Make automatic merges respect our merge source normalization requirements.

This fixes issue #4313 'replaced merges source causes assertion during
automatic merge' and partially fixes issue #4138 'replacement in merge
source not notified correctly', specifically the part detailed here:
http://subversion.tigris.org/issues/show_bug.cgi?id=4138#desc4

* subversion/libsvn_client/merge.c
  (do_automatic_merge_locked): Normalize the merge sources passed to
   do_merge().

* subversion/tests/cmdline/merge_automatic_tests.py
  (auto_merge_handles_replacements_in_merge_source): Remove XFail decorator
   and tweak comment re failure status.



git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1443040 13f79535-47bb-0310-9956-ffa450edef68