When merging a replacement, don't try the add part if the delete part failed
with a tree conflict. This resolves issue #4011.

* subversion/libsvn_client/merge.c
  (merge_file_opened,
   merge_dir_opened): Update action earlier to avoid recording edit on adds.
       Skip adds when the matching delete was a tree conflict.

* subversion/tests/cmdline/merge_tree_conflict_tests.py
  (merge_replace_on_del_fails): Remove XFail marker.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1443275 13f79535-47bb-0310-9956-ffa450edef68