keep track of the stage we're at in pairing

This avoids us responding to our own pairing messages, as well
as ignoring any out of order messages that might be received somehow.

Assistant/WebApp/Configurators/Pairing.hs

@@ -95,9 +95,9 @@ startPairing stage oncancel displaysecret secret = do
 		<*> pure (sshPubKey keypair)
 		<*> liftIO genUUID
 	liftIO $ do
-		let sender = multicastPairMsg Nothing secret stage pairdata
-		let pip = PairingInProgress secret Nothing keypair pairdata
-		startSending dstatus pip $ sendrequests sender dstatus urlrender
+		let sender = multicastPairMsg Nothing secret pairdata
+		let pip = PairingInProgress secret Nothing keypair pairdata stage
+		startSending dstatus pip stage $ sendrequests sender dstatus urlrender
 	lift $ redirect $ InprogressPairR $ toSecretReminder displaysecret
 	where
 		{- Sends pairing messages until the thread is killed,
@@ -108,7 +108,7 @@ startPairing stage oncancel displaysecret secret = do
 		 - have been on a page specific to the in-process pairing
 		 - that just stopped, so can't go back there.
 		 -}
-		sendrequests sender dstatus urlrender = do
+		sendrequests sender dstatus urlrender _stage = do
 			tid <- myThreadId
 			let selfdestruct = AlertButton
 				{ buttonLabel = "Cancel"
@@ -118,7 +118,7 @@ startPairing stage oncancel displaysecret secret = do
 					killThread tid
 				}
 			alertDuring dstatus (pairingAlert selfdestruct) $ do
-				_ <- E.try sender :: IO (Either E.SomeException ())
+				_ <- E.try (sender stage) :: IO (Either E.SomeException ())
 				return ()
 
 data InputSecret = InputSecret { secretText :: Maybe Text }