Apply a simple tweak which fixes the issue identified in r1605866, when not
noticing ancestry: drive the editor as if it is a checkout for local copies.

* subversion/libsvn_client/diff.c
  (diff_repos_wc): When reporting a copy in ignore ancestry mode, report the
    copy as from r0, to make the repository send all nodes as additions.

* subversion/tests/cmdline/diff_tests.py
  (diff_replaced_moved): Remove XFail marker.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1605869 13f79535-47bb-0310-9956-ffa450edef68