simplify transferr protocol

Messages/Progress.hs

@@ -116,7 +116,10 @@ metered' st othermeter msize showoutput a = go st
 			a meter (combinemeter m)
 		| otherwise = nometer
 	go (MessageState { outputType = SerializedOutput h _ }) = do
-		liftIO $ outputSerialized h $ BeginProgressMeter msize
+		liftIO $ outputSerialized h BeginProgressMeter
+		case msize of
+			Just sz -> liftIO $ outputSerialized h $ UpdateProgressMeterTotalSize sz
+			Nothing -> noop
 		szv <- liftIO $ newIORef msize
 		meter <- liftIO $ mkMeter msize $ \_ msize' _old new -> do
 			case msize' of

Messages/Serialized.hs

@@ -63,11 +63,11 @@ relaySerializedOutput getso sendsor meterreport runannex = go Nothing
 					outputSerialized h $ JSONObject b
 				_ -> q
 			loop st
-		Left (BeginProgressMeter sz) -> do
+		Left BeginProgressMeter -> do
 			ost <- runannex (Annex.getState Annex.output)
 			-- Display a progress meter while running, until
 			-- the meter ends or a final value is returned.
-			metered' ost Nothing sz (runannex showOutput) 
+			metered' ost Nothing Nothing (runannex showOutput) 
 				(\meter meterupdate -> loop (Just (meter, meterupdate)))
 				>>= \case
 					Right r -> return (Right r)