Make a regression test a bit stricter and remove some bad whitespace.

* subversion/tests/cmdline/lock_tests.py
  (lock_path_not_in_head): Remove a workaround for the old serf error message.
  (drop_locks_on_parent_deletion,
   copy_with_lock): Remove tabs.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1552108 13f79535-47bb-0310-9956-ffa450edef68