Backport r1455352 onto 1.6.x:

 * r1455352
   Improve logic in mod_dav_svn's implementation of lock. 
   Votes:
     +1: breser, philip, cmpilato

--T1is line, and those below, will be ignored--

M   subversion/mod_dav_svn/lock.c


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/1.6.x@1462326 13f79535-47bb-0310-9956-ffa450edef68