merge revision 118702 from trunk to 1.4 -- Fixes a bug in chan_iax that uses send_command to poke a peer while a channel is unlocked in some cases, and because it can cause seemingly random failures could be related to some bugs in the tracker...

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@118716 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_iax2.c

@@ -8878,7 +8878,11 @@ static int iax2_poke_peer(struct iax2_peer *peer, int heldcall)
 		peer_unref(peer);
 
 	/* And send the poke */
-	send_command(iaxs[peer->callno], AST_FRAME_IAX, IAX_COMMAND_POKE, 0, NULL, 0, -1);
+	ast_mutex_lock(&iaxsl[peer->callno]);
+	if (iaxs[peer->callno]) {
+		send_command(iaxs[peer->callno], AST_FRAME_IAX, IAX_COMMAND_POKE, 0, NULL, 0, -1);
+	}
+	ast_mutex_unlock(&iaxsl[peer->callno]);
 
 	return 0;
 }