Ensure Asterisk acknowledges ACKs to 4xx on Replaces errors

Asterisk was not setting pendinginvite in the upper half of
handle_request_invite such that the 4xx was retransmitted repeatedly even
though an ack was received for every retransmission.

(closes issue ASTERISK-19303)
Reported by: Jon Tsiros
Patches:
  fix-19303.patch uploaded by Jeremiah Gowdy (license 6358)

........

Merged revisions 358115 from http://svn.asterisk.org/svn/asterisk/branches/1.8


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/10@358116 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -22974,6 +22974,9 @@ static int handle_request_invite(struct sip_pvt *p, struct sip_request *req, int
 				}
 			}
 			transmit_response_reliable(p, "491 Request Pending", req);
+			p->pendinginvite = seqno;
+			check_via(p, req);
+			copy_request(&p->initreq, req);
 			ast_debug(1, "Got INVITE on call where we already have pending INVITE, deferring that - %s\n", p->callid);
 			/* Don't destroy dialog here */
 			res = INV_REQ_FAILED;
@@ -22993,6 +22996,9 @@ static int handle_request_invite(struct sip_pvt *p, struct sip_request *req, int
 		if (p->owner) {
 			ast_debug(3, "INVITE w Replaces on existing call? Refusing action. [%s]\n", p->callid);
 			transmit_response_reliable(p, "400 Bad request", req);	/* The best way to not not accept the transfer */
+			p->pendinginvite = seqno;
+			check_via(p, req);
+			copy_request(&p->initreq, req);
 			/* Do not destroy existing call */
 			res = INV_REQ_ERROR;
 			goto request_invite_cleanup;
@@ -23010,6 +23016,9 @@ static int handle_request_invite(struct sip_pvt *p, struct sip_request *req, int
 			sip_scheddestroy(p, DEFAULT_TRANS_TIMEOUT);
 			p->invitestate = INV_COMPLETED;
 			res = INV_REQ_ERROR;
+			p->pendinginvite = seqno;
+			check_via(p, req);
+			copy_request(&p->initreq, req);
 			goto request_invite_cleanup;
 		}
 
@@ -23111,6 +23120,9 @@ static int handle_request_invite(struct sip_pvt *p, struct sip_request *req, int
 			refer_locked = 0;
 			p->invitestate = INV_COMPLETED;
 			res = INV_REQ_ERROR;
+			p->pendinginvite = seqno;
+			check_via(p, req);
+			copy_request(&p->initreq, req);
 			goto request_invite_cleanup;
 		}
 	}