Merged revisions 343900 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/10

........
  r343900 | dvossel | 2011-11-08 12:29:33 -0600 (Tue, 08 Nov 2011) | 11 lines
  
  Fixes regression caused by r343635
  
  There was a missing unlock for a function return that is only
  present in Asterisk 10 and Asterisk Trunk.
  
  (closes issue ASTERISK-18839)
  Reported by: Michael L. Young
  Patches:
      asterisk-18839-missing-lock-trunk-v2.diff (License #5026) patch uploaded by Michael L. Young
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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@343905 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -25938,6 +25938,7 @@ static int sip_send_mwi_to_peer(struct sip_peer *peer, int cache_only)
 		peer_mailboxes_to_str(&mailbox_str, peer);
 		/* if there is no mailbox do nothing */
 		if (ast_strlen_zero(mailbox_str->str)) {
+			ao2_unlock(peer);
 			return -1;
 		}
 		ao2_unlock(peer);