In mod_dav_svn: Properly forward post lock and post unlock failures that are
wrapped with different errors like SVN_ERR_REPOS_POST_LOCK_HOOK_FAILED,
instead of just reporting a generic message.

This will make 'svn' properly report:
svn: E165008: Locking succeeded, but post-lock hook failed
instead of
svn: E165008: Failed to create new lock.

which more accurately describes the result.

* subversion/mod_dav_svn/lock.c
  (append_locks,
   refresh_locks): Check for hook as error cause instead of only as
     outer error code.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1622235 13f79535-47bb-0310-9956-ffa450edef68