INVITE 403 Forbidden response always retransmits the maximum times.

Asterisk sends a 403 Forbidden response if authentication fails for an
INVITE as required.  However, it ignores the ACK and keeps retransmitting
the response.

* Made not delete the to-tag in the dialog so the expected ACK can be
matched with the dialog and stop the retransmissions.


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@327211 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -21958,7 +21958,6 @@ static int handle_request_invite(struct sip_pvt *p, struct sip_request *req, int
 			}
 			p->invitestate = INV_COMPLETED;
 			sip_scheddestroy(p, DEFAULT_TRANS_TIMEOUT);
-			ast_string_field_set(p, theirtag, NULL);
 			res = 0;
 			goto request_invite_cleanup;
 		}