avoid using concurrent-output at all when --quiet or --json

Of course, it wasn't used much in those modes, because normal output is
avoided. But it was still initialized and used in a few places,
including a call to hideRegionsWhile.

CmdLine/Action.hs

@@ -181,11 +181,13 @@ allowConcurrentOutput a = do
 		c <- liftIO getNumCapabilities
 		when (n > c) $
 			liftIO $ setNumCapabilities n
-		ifM (liftIO concurrentOutputSupported)
-			( Regions.displayConsoleRegions $
-				goconcurrent' True
-			, goconcurrent' False
-			)
+		withMessageState $ \s -> case outputType s of
+			NormalOutput -> ifM (liftIO concurrentOutputSupported)
+				( Regions.displayConsoleRegions $
+					goconcurrent' True
+				, goconcurrent' False
+				)
+			_ -> goconcurrent' False
 	goconcurrent' b = bracket_ (setup b) cleanup a
 	setup = setconcurrentoutputenabled
 	cleanup = do

Messages.hs

@@ -270,4 +270,4 @@ prompt a = go =<< Annex.getState Annex.concurrency
 		bracketIO
 			(takeMVar l)
 			(putMVar l)
-			(const $ hideRegionsWhile a)
+			(const $ hideRegionsWhile s a)

Messages/Concurrent.hs

@@ -123,9 +123,11 @@ concurrentOutputSupported = return True -- Windows is always unicode
  - This needs a new enough version of concurrent-output; otherwise
  - the regions will not be hidden, but the action still runs, garbling the
  - display. -}
-hideRegionsWhile :: Annex a -> Annex a
+hideRegionsWhile :: MessageState -> Annex a -> Annex a
 #if MIN_VERSION_concurrent_output(1,9,0)
-hideRegionsWhile a = bracketIO setup cleanup go
+hideRegionsWhile s a 
+	| concurrentOutputEnabled s = bracketIO setup cleanup go
+	| otherwise = a
   where
 	setup = Regions.waitDisplayChange $ swapTMVar Regions.regionList []
 	cleanup = void . atomically . swapTMVar Regions.regionList