get, move, copy, mirror: Added --failed switch which retries failed copies/moves

Note that get --from foo --failed will get things that a previous get --from bar
tried and failed to get, etc. I considered making --failed only retry
transfers from the same remote, but it was easier, and seems more useful,
to not have the same remote requirement.

Noisy due to some refactoring into Types/

Command.hs

@@ -1,6 +1,6 @@
 {- git-annex command infrastructure
  -
- - Copyright 2010-2015 Joey Hess <id@joeyh.name>
+ - Copyright 2010-2016 Joey Hess <id@joeyh.name>
  -
  - Licensed under the GNU GPL version 3 or higher.
  -}
@@ -26,6 +26,8 @@ import qualified Git
 import Annex.Init
 import Config
 import Utility.Daemon
+import Types.Transfer
+import Types.ActionItem
 
 {- Generates a normal Command -}
 command :: String -> CommandSection -> String -> CmdParamsDesc -> (CmdParamsDesc -> CommandParser) -> Command
@@ -91,6 +93,15 @@ stop = return Nothing
 stopUnless :: Annex Bool -> Annex (Maybe a) -> Annex (Maybe a)
 stopUnless c a = ifM c ( a , stop )
 
+{- When acting on a failed transfer, stops unless it was in the specified
+ - direction. -}
+checkFailedTransferDirection :: ActionItem -> Direction -> Annex (Maybe a) -> Annex (Maybe a)
+checkFailedTransferDirection ai d = stopUnless (pure check)
+  where
+	check = case actionItemTransferDirection ai of
+		Nothing -> True
+		Just d' -> d' == d
+
 commonChecks :: [CommandCheck]
 commonChecks = [repoExists]