propagate git-annex -c on to transferrer child process

git -c was already propagated via environment, but need this for
consistency.

Also, notice it does not use gitAnnexChildProcess to run the
transferrer. So nothing is done about avoid it taking the
pid lock. It's possible that the caller is already doing something that
took the pid lock, and if so, the transferrer will certianly fail,
since it needs to take the pid lock too. This may prevent combining
annex.stalldetection with annex.pidlock, but I have not verified it's
really a problem. If it was, it seems git-annex would have to take
the pid lock when starting a transferrer, and hold it until shutdown,
or would need to take pid lock when starting to use a transferrer,
and hold it until done with a transfer and then drop it. The latter
would require starting the transferrer with pid locking disabled for the
child process, so assumes that the transferrer does not do anyting that
needs locking when not running a transfer.

Assistant/Threads/Transferrer.hs

@@ -11,15 +11,15 @@ import Assistant.Common
 import Assistant.TransferQueue
 import Assistant.TransferSlots
 import Types.Transfer
-import Annex.Path
+import Annex.TransferrerPool
 import Utility.Batch
 
 {- Dispatches transfers from the queue. -}
 transfererThread :: NamedThread
 transfererThread = namedThread "Transferrer" $ do
-	program <- liftIO programPath
-	batchmaker <- liftIO getBatchCommandMaker
-	forever $ inTransferSlot program batchmaker $
+	rt <- liftAnnex . mkRunTransferrer
+		=<< liftIO getBatchCommandMaker
+	forever $ inTransferSlot rt $
 		maybe (return Nothing) (uncurry genTransfer)
 			=<< getNextTransfer notrunning
   where

Assistant/TransferSlots.hs

@@ -34,7 +34,6 @@ import qualified Remote
 import qualified Types.Remote as Remote
 import Annex.Content
 import Annex.Wanted
-import Annex.Path
 import Utility.Batch
 import Types.NumCopies
 
@@ -55,17 +54,17 @@ type TransferGenerator = Assistant (Maybe (Transfer, TransferInfo, Transferrer -
 {- Waits until a transfer slot becomes available, then runs a
  - TransferGenerator, and then runs the transfer action in its own thread. 
  -}
-inTransferSlot :: FilePath -> BatchCommandMaker -> TransferGenerator -> Assistant ()
-inTransferSlot program batchmaker gen = do
+inTransferSlot :: RunTransferrer -> TransferGenerator -> Assistant ()
+inTransferSlot rt gen = do
 	flip MSemN.wait 1 <<~ transferSlots
-	runTransferThread program batchmaker =<< gen
+	runTransferThread rt =<< gen
 
 {- Runs a TransferGenerator, and its transfer action,
  - without waiting for a slot to become available. -}
-inImmediateTransferSlot :: FilePath -> BatchCommandMaker -> TransferGenerator -> Assistant ()
-inImmediateTransferSlot program batchmaker gen = do
+inImmediateTransferSlot :: RunTransferrer -> TransferGenerator -> Assistant ()
+inImmediateTransferSlot rt gen = do
 	flip MSemN.signal (-1) <<~ transferSlots
-	runTransferThread program batchmaker =<< gen
+	runTransferThread rt =<< gen
 
 {- Runs a transfer action, in an already allocated transfer slot.
  - Once it finishes, frees the transfer slot.
@@ -77,25 +76,25 @@ inImmediateTransferSlot program batchmaker gen = do
  - then pausing the thread until a ResumeTransfer exception is raised,
  - then rerunning the action.
  -}
-runTransferThread :: FilePath -> BatchCommandMaker -> Maybe (Transfer, TransferInfo, Transferrer -> Assistant ()) -> Assistant ()
-runTransferThread _ _ Nothing = flip MSemN.signal 1 <<~ transferSlots
-runTransferThread program batchmaker (Just (t, info, a)) = do
+runTransferThread :: RunTransferrer -> Maybe (Transfer, TransferInfo, Transferrer -> Assistant ()) -> Assistant ()
+runTransferThread _ Nothing = flip MSemN.signal 1 <<~ transferSlots
+runTransferThread rt (Just (t, info, a)) = do
 	d <- getAssistant id
 	mkcheck <- checkNetworkConnections 
 		<$> getAssistant daemonStatusHandle
 	aio <- asIO1 a
-	tid <- liftIO $ forkIO $ runTransferThread' mkcheck program batchmaker d aio
+	tid <- liftIO $ forkIO $ runTransferThread' mkcheck rt d aio
 	updateTransferInfo t $ info { transferTid = Just tid }
 
-runTransferThread' :: MkCheckTransferrer -> FilePath -> BatchCommandMaker -> AssistantData -> (Transferrer -> IO ()) -> IO ()
-runTransferThread' mkcheck program batchmaker d run = go
+runTransferThread' :: MkCheckTransferrer -> RunTransferrer -> AssistantData -> (Transferrer -> IO ()) -> IO ()
+runTransferThread' mkcheck rt d run = go
   where
 	go = catchPauseResume $ do
 		p <- runAssistant d $ liftAnnex $ 
 			Annex.getState Annex.transferrerpool
 		signalactonsvar <- runAssistant d $ liftAnnex $
 			Annex.getState Annex.signalactions
-		withTransferrer' True signalactonsvar mkcheck program batchmaker p run
+		withTransferrer' True signalactonsvar mkcheck rt p run
 	pause = catchPauseResume $
 		runEvery (Seconds 86400) noop
 	{- Note: This must use E.try, rather than E.catch.
@@ -303,9 +302,9 @@ startTransfer t = do
 		alterTransferInfo t $ \i -> i { transferPaused = False }
 		liftIO $ throwTo tid ResumeTransfer
 	start info = do
-		program <- liftIO programPath
-		batchmaker <- liftIO getBatchCommandMaker
-		inImmediateTransferSlot program batchmaker $
+		rt <- liftAnnex . mkRunTransferrer
+			=<< liftIO getBatchCommandMaker
+		inImmediateTransferSlot rt $
 			genTransfer t info
 
 getCurrentTransfers :: Assistant TransferMap