fix serveGet hang

This came down to SendBytes waiting on the waitv. Nothing ever filled
it.

Only Annex.Proxy needs the waitv, and it handles filling it. So make it
optional.

P2P/IO.hs

@@ -79,7 +79,7 @@ mkRunState mk = do
 
 data P2PHandle
 	= P2PHandle Handle
-	| P2PHandleTMVar (TMVar (Either L.ByteString Message)) (TMVar ())
+	| P2PHandleTMVar (TMVar (Either L.ByteString Message)) (Maybe (TMVar ()))
 
 data P2PConnection = P2PConnection
 	{ connRepo :: Maybe Repo
@@ -217,7 +217,7 @@ runNet runst conn runner f = case f of
 			Right () -> runner next
 	ReceiveMessage next ->
 		let protoerr = return $ Left $
-			ProtoFailureMessage "protocol error 1"
+			ProtoFailureMessage "protocol error"
 		    gotmessage m = do
 			liftIO $ debugMessage conn "P2P <" m
 			runner (next (Just m))
@@ -246,11 +246,14 @@ runNet runst conn runner f = case f of
 					Right False -> return $ Left $
 						ProtoFailureMessage "short data write"
 					Left e -> return $ Left $ ProtoFailureException e
-			P2PHandleTMVar mv waitv -> do
+			P2PHandleTMVar mv mwaitv -> do
 				liftIO $ atomically $ putTMVar mv (Left b)
-				-- Wait for the whole bytestring to be
-				-- processed. Necessary due to lazyiness.
-				liftIO $ atomically $ takeTMVar waitv
+				case mwaitv of
+					-- Wait for the whole bytestring to
+					-- be processed.
+					Just waitv -> liftIO $ atomically $
+						takeTMVar waitv
+					Nothing -> return ()
 				runner next
 	ReceiveBytes len p next ->
 		case connIhdl conn of
@@ -264,7 +267,7 @@ runNet runst conn runner f = case f of
 				liftIO (atomically (takeTMVar mv)) >>= \case
 					Left b -> runner (next b)
 					Right _ -> return $ Left $
-						ProtoFailureMessage "protocol error 2"
+						ProtoFailureMessage "protocol error"
 	CheckAuthToken _u t next -> do
 		let authed = connCheckAuth conn t
 		runner (next authed)