Fix the breakage of SVNListParentPath caused by the translate_name hook.

* subversion/mod_dav_svn/mod_dav_svn.c
  (dav_svn__translate_name): dav_svn_split_uri() returns an error when hitting
    the root_dir, which means SVNListParentPath doesn't work.  Delay reutrning
    the error so we can check if the repos_basename is missing for
    SVNParentPath configurations.  


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1541790 13f79535-47bb-0310-9956-ffa450edef68