Fix a latent bug before it bites us:.
Fix a latent bug before it bites us:.

* subversion/libsvn_ra_dav/session.c:
  (svn_ra_dav__do_get_uuid):  The server might not actually send a uuid, so
   check to make sure that we actually got one before dereferencing.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@845307 13f79535-47bb-0310-9956-ffa450edef68

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