Add another XFail test for issue 4111 to show NODES problem.

* subversion/tests/libsvn_wc/op-depth-test.c
  (update_child_under_add): New test.
  (test_funcs): Add new test.

* subversion/tests/cmdline/update_tests.py
  (update_child_below_add): Tweak comment.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1448775 13f79535-47bb-0310-9956-ffa450edef68