Merged revisions 164350 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/1.4

........
  r164350 | file | 2008-12-15 14:11:21 -0400 (Mon, 15 Dec 2008) | 6 lines
  
  Do not try to unlock a non-existant channel if the transfer fails.
  (closes issue #13800)
  Reported by: dwagner
  Patches:
        asterisk-1.4.22-chan-sip-nullp.patch uploaded by tweety (license 608)
........


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@164351 65c4cc65-6c06-0410-ace0-fbb531ad65f3