Revert "add catFileIndex"

This interface is not a good idea, because a running git cat-file --batch
does not notice when existing files in the index are changed.

Annex/CatFile.hs

@@ -7,7 +7,6 @@
 
 module Annex.CatFile (
 	catFile,
-	catFileIndex,
 	catObject,
 	catObjectDetails,
 	catFileHandle
@@ -26,11 +25,6 @@ catFile branch file = do
 	h <- catFileHandle
 	liftIO $ Git.CatFile.catFile h branch file
 
-catFileIndex :: FilePath -> Annex L.ByteString
-catFileIndex file = do
-	h <- catFileHandle
-	liftIO $ Git.CatFile.catFileIndex h file
-
 catObject :: Git.Ref -> Annex L.ByteString
 catObject ref = do
 	h <- catFileHandle

Git/CatFile.hs

@@ -10,7 +10,6 @@ module Git.CatFile (
 	catFileStart,
 	catFileStop,
 	catFile,
-	catFileIndex,
 	catObject,
 	catObjectDetails,
 ) where
@@ -41,10 +40,6 @@ catFileStop = CoProcess.stop
 catFile :: CatFileHandle -> Branch -> FilePath -> IO L.ByteString
 catFile h branch file = catObject h $ Ref $ show branch ++ ":" ++ file
 
-{- Reads a file from the index. -}
-catFileIndex :: CatFileHandle -> FilePath -> IO L.ByteString
-catFileIndex h file = catObject h $ Ref $ ':' : file
-
 {- Uses a running git cat-file read the content of an object.
  - Objects that do not exist will have "" returned. -}
 catObject :: CatFileHandle -> Ref -> IO L.ByteString