Resolve issue #4666 "svnmucc fails to delete directories that contain just deletes", by handling this special corner case.
* subversion/libsvn_client/mtcc.c (mtcc_op_contains_non_delete): New function. (svn_client__mtcc_add_delete): Rename to... (mtcc_add_delete): ... and allow deleting directories that contain just deletes. (svn_client__mtcc_add_delete): New function around mtcc_add_delete. (svn_client__mtcc_add_move): Keep old behavior to avoid regression in case we move something that contains deletes. (Unsupported scenario in current implementation).
* subversion/tests/libsvn_client/mtcc-test.c (test_funcs): Remove XFail from test_move_and_delete_ancestor.