Add a regression test for issue #4221 'Trivial merge of a binary file with
svn:keywords raises a conflict'.

* subversion/tests/cmdline/merge_tests.py
  (merge_binary_file_with_keywords): New test, XFail.
  (test_list): Run it.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1430425 13f79535-47bb-0310-9956-ffa450edef68