Fix issue #4367 'merge to shallow WC, repeat merge to infinite depth WC is
broken'.

* subversion/libsvn_client/merge.c

  (merge_dir_opened,
   merge_dir_added): A merge may be broken into multiple editor drives.
   One drive may add a directory and then a later one might delete it.  So
   don't assume the copy from revision (which must always exist for a merge)
   on an added directory is dictated by the larger merge source, use the
   (possibly different) revision from the editor drive. 

* subversion/tests/cmdline/merge_tests.py

  (merge_to_empty_target_merge_to_infinite_target): Remove XFail decorator.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1483947 13f79535-47bb-0310-9956-ffa450edef68