Make the behavior of post lock and unlock hooks consistent between DAV and
the other ra implementations.

* subversion/libsvn_ra_serf/lock.c
  (run_locks): Report unlocks as succeeded before reporting the lock failure.

* subversion/mod_dav_svn/lock.c
  (append_locks,
   remove_lock): Specialize the behavior for post hook failures.

* subversion/mod_dav_svn/util.c
  (dav_svn__convert_err): Don't hide post unlock errors.

* subversion/tests/cmdline/lock_tests.py
  (failing_post_hooks): Remove XFail marker for DAV. Update expected errors,
    while keeping the working copy state checks.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1622244 13f79535-47bb-0310-9956-ffa450edef68