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.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@871626 13f79535-47bb-0310-9956-ffa450edef68

wbond/subversion,wbond/subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion