Update the error handling of the ra_serf update handler to properly call
abort_edit on failed edit operations.

* subversion/libsvn_ra_serf/update.c
  (report_context_t): Rename update_baton to edit_baton.
  (ensure_dir_opened): Update caller.
  (update_closed): Update caller.
  (process_editor_report): New function, extracted from...
  (finish_report): ... this function which is now a caller.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1557699 13f79535-47bb-0310-9956-ffa450edef68