Disable requests for sr's that already exist

auth/confirm.go

@@ -120,7 +120,9 @@ func (s *state) confirm(partner contact.Contact, serviceTag string) (
 			s.event.Report(10, "Auth", "SendConfirmError", em)
 		}
 
-		s.backupTrigger("confirmed authenticated channel")
+		if s.backupTrigger != nil {
+			s.backupTrigger("confirmed authenticated channel")
+		}
 
 		jww.INFO.Printf("Confirming Auth from %s to %s, msgDigest: %s",
 			partner.ID, s.e2e.GetReceptionID(),