get, move, copy: Now refuse to do anything when the requested file transfer is already in progress by another process.

Note this is per-remote, so trying to get the same file from multiple
remotes can still let duplicate downloads run. (And uploading the same file
to multiple remotes is not duplicate at all of course.)

get, move, and copy are the only git-annex subcommands that transfer
files, but there's still git-annex-shell recvkey and sendkey to deal with too.

I considered modifying retrieveKeyFile or getViaTmp, but they are called
by other code that does not involve expensive file transfers (migrate)
or that does file transfers that should not be checked by this (fsck --from).

Command/Move.hs

@@ -16,6 +16,7 @@ import qualified Remote
 import Annex.UUID
 import qualified Option
 import Logs.Presence
+import Logs.Transfer
 
 def :: [Command]
 def = [withOptions options $ command "move" paramPaths seek
@@ -68,9 +69,9 @@ toStart dest move file key = do
 		then stop -- not here, so nothing to do
 		else do
 			showMoveAction move file
-			next $ toPerform dest move key
-toPerform :: Remote -> Bool -> Key -> CommandPerform
-toPerform dest move key = moveLock move key $ do
+			next $ toPerform dest move key file
+toPerform :: Remote -> Bool -> Key -> FilePath -> CommandPerform
+toPerform dest move key file = moveLock move key $ do
 	-- Checking the remote is expensive, so not done in the start step.
 	-- In fast mode, location tracking is assumed to be correct,
 	-- and an explicit check is not done, when copying. When moving,
@@ -88,7 +89,7 @@ toPerform dest move key = moveLock move key $ do
 			stop
 		Right False -> do
 			showAction $ "to " ++ Remote.name dest
-			ok <- Remote.storeKey dest key
+			ok <- upload dest key file $ Remote.storeKey dest key
 			if ok
 				then finish
 				else do
@@ -118,7 +119,7 @@ fromStart src move file key
 	where
 		go = stopUnless (fromOk src key) $ do
 			showMoveAction move file
-			next $ fromPerform src move key
+			next $ fromPerform src move key file
 fromOk :: Remote -> Key -> Annex Bool
 fromOk src key
 	| Remote.hasKeyCheap src =
@@ -129,11 +130,11 @@ fromOk src key
 			u <- getUUID
 			remotes <- Remote.keyPossibilities key
 			return $ u /= Remote.uuid src && elem src remotes
-fromPerform :: Remote -> Bool -> Key -> CommandPerform
-fromPerform src move key = moveLock move key $
+fromPerform :: Remote -> Bool -> Key -> FilePath -> CommandPerform
+fromPerform src move key file = moveLock move key $
 	ifM (inAnnex key)
 		( handle move True
-		, do
+		, download src key file $ do
 			showAction $ "from " ++ Remote.name src
 			ok <- getViaTmp key $ Remote.retrieveKeyFile src key
 			handle move ok