simpler way to do this

Remove old code that can be trivially implemented using async in a much
nicer way (that is async exception safe).

I've audited all forkOS calls (except for ones in the assistant),
and this was the last remaining one that is not async exception safe.
The rest look ok to me.

Assistant/Sync.hs

@@ -17,7 +17,6 @@ import Assistant.DaemonStatus
 import Assistant.ScanRemotes
 import Assistant.RemoteControl
 import qualified Command.Sync
-import Utility.Parallel
 import qualified Git
 import qualified Git.Command
 import qualified Remote
@@ -43,6 +42,7 @@ import Database.Export
 import Data.Time.Clock
 import qualified Data.Map as M
 import Control.Concurrent
+import Control.Concurrent.Async
 
 {- Syncs with remotes that may have been disconnected for a while.
  - 
@@ -177,6 +177,11 @@ parallelPush g rs a = do
 		<*> (Remote.getRepo r >>= \repo ->
 			sshOptionsTo repo (Remote.gitconfig r) g)
 
+inParallel :: (v -> IO Bool) -> [v] -> IO ([v], [v])
+inParallel a l = (\(t,f) -> (map fst t, map fst f)) 
+	. partition snd 
+	. zip l <$> mapConcurrently a l
+
 {- Displays an alert while running an action that syncs with some remotes,
  - and returns any remotes that it failed to sync with.
  -