* subversion/libsvn_ra_serf/commit.c
  (open_root): Prefer detailed error messages when available for the pre-v2
     code path, like we handle it for v2 commits.
  (add_directory): Prefer detailed error messages.
  (add_file): Explicitly handle status 404.
  (abort_edit): Handle errors locally to allow ignoring a few status codes,
     but use the standard function.

* subversion/libsvn_ra_serf/lock.c
  (handle_lock): Remove duplicated status handling code. The standard ra_serf
     handler already performs this step.

* subversion/libsvn_ra_serf/util.c
  (svn_ra_serf__error_on_status): Add specialized message for http status 500
     and remove stray newline from error message for unexpected error status.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1553267 13f79535-47bb-0310-9956-ffa450edef68