ra_serf: Correctly clear a server error if it's already reported based on the status code.
ra_serf: Correctly clear a server error if it's already reported based on the
status code.

* subversion/libsvn_ra_serf/commit.c
  (checkout_dir): Clear server error.

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