Following up on r1557207, properly handle <S:fetch-props /> requests from
servers in the ra-serf transition based xml parser.

This resolves a regression of the trunk code against Subversion <= 1.8 when
talking to Subversion 1.6 or earlier repositories in non bulk mode.

Most likely this resolves issue #4486.

The easiest way to reproduce a hard failure I could find was
$ svn co http://svn.webdav.org/repos/projects/neon/trunk neon \
      --config-option servers:global:http-bulk-updates=false

(Neon is hosted by a Subversion 1.3 mod_dav_svn)

* subversion/libsvn_ra_serf/update.c
  (report_state_e): Add fetch props, and document a few other states that may
    be seen with older repositories.
  (update_ttable): Add a few missing states.
  (update_opened): Handle fetch-props.
  (update_closed): Add commented handlers for 3 special properties.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1582023 13f79535-47bb-0310-9956-ffa450edef68