Resolve the remaining bits of issue #3314 'DAV can overwrite directories
during copy' by using even more standard error handling in ra_serf and
removing a temporary workaround.

* subversion/libsvn_ra_serf/commit.c
  (open_root): Use standard error reporting.
  (add_directory): Remove comment.
  (add_file): Following up on r1553539 and r1553517, remove hack that
    allowed some overwrites to pass unnoticed.
  (abort_edit): Use standard error reporting.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1553546 13f79535-47bb-0310-9956-ffa450edef68