Following up on r1446390, also report the left version of added directories
as r0, but this is currently libsvn_client specific as the old diff
callbacks don't handle this revision.

* subversion/libsvn_client/diff.c
  (diff_dir_props_changed): Report revision 0 for added nodes.

* subversion/tests/cmdline/diff_tests.py
  (diff_repos_wc_add_with_props): X was added in r2, so r1 is clearly wrong.
  (diff_dir_replaced_by_dir): New regression test.
  (test_list): Add test.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1446405 13f79535-47bb-0310-9956-ffa450edef68