Fix issue #4175.
Fix issue #4175.

This is due to EAGAIN being returned while we are in the 404 XML handler after
we have marked it as done.  ra_serf ends up re-using the memory space that
serf has kept for the last uncompleted request as it doesn't think the
request is done yet.

* subversion/libsvn_ra_serf/util.c
  (handle_server_error): Allow EOF & EAGAIN to be returned from drain_bucket
  call.
  (svn_ra_serf__handle_xml_parser): Delay noting the item is done until after
  we have received the EOF from the discarded body.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion