make maybeShowJSON also add to the buffer

Messages.hs

@@ -155,15 +155,11 @@ indent = intercalate "\n" . map (\l -> "  " ++ l) . lines
 
 {- Shows a JSON chunk only when in json mode. -}
 maybeShowJSON :: JSONChunk v -> Annex ()
-maybeShowJSON v = withMessageState $ \s -> case outputType s of
-	JSONOutput -> liftIO $ JSON.add v
-	_ -> return ()
+maybeShowJSON v = void $ withMessageState $ outputJSON (JSON.add v) False
 
 {- Shows a complete JSON value, only when in json mode. -}
 showFullJSON :: JSONChunk v -> Annex Bool
-showFullJSON v = withMessageState $ \s -> case outputType s of
-	JSONOutput -> liftIO $ JSON.complete v >> return True
-	_ -> return False
+showFullJSON v = withMessageState $ outputJSON (JSON.complete v) True
 
 {- Performs an action that outputs nonstandard/customized output, and
  - in JSON mode wraps its output in JSON.start and JSON.end, so it's

Messages/Internal.hs

@@ -26,8 +26,13 @@ outputMessage' endmessage json msg = withMessageState $ \s -> case outputType s
 	NormalOutput
 		| concurrentOutputEnabled s -> concurrentMessage s False msg q
 		| otherwise -> liftIO $ flushed $ putStr msg
+	JSONOutput -> void $ outputJSON json endmessage s
+	QuietOutput -> q
+
+outputJSON :: IO () -> Bool -> MessageState -> Annex Bool
+outputJSON json endmessage s = case outputType s of
 	JSONOutput
-		| concurrentOutputEnabled s ->
+		| concurrentOutputEnabled s -> do
 			-- Buffer json fragments until end is reached.
 			if endmessage
 				then do
@@ -38,8 +43,11 @@ outputMessage' endmessage json msg = withMessageState $ \s -> case outputType s
 						json
 				else Annex.changeState $ \st ->
 				        st { Annex.output = s { jsonBuffer = json : jsonBuffer s } }
-		| otherwise -> liftIO $ flushed json
-	QuietOutput -> q
+			return True
+		| otherwise -> do
+			liftIO $ flushed json
+			return True
+	_ -> return False
 
 outputError :: String -> Annex ()
 outputError msg = withMessageState $ \s ->