fixes failed SIP Directed pickup resulting in dead channel

(closes issue #17339)
Reported by: one47
Patches:
      sip_magic_pickup2 uploaded by one47 (license 23)
Tested by: one47, dvossel


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@266006 65c4cc65-6c06-0410-ace0-fbb531ad65f3