add support for using hashDirLower in addition to hashDirMixed

Supporting multiple directory hash types will allow converting to a
different one, without a flag day.

gitAnnexLocation now checks which of the possible locations have a file.
This means more statting of files. Several places currently use
gitAnnexLocation and immediately check if the returned file exists;
those need to be optimised.

Annex/Content.hs

@@ -43,12 +43,12 @@ import Annex.Exception
 
 {- Checks if a given key's content is currently present. -}
 inAnnex :: Key -> Annex Bool
-inAnnex = inAnnex' doesFileExist
+inAnnex = inAnnex' $ doesFileExist
 inAnnex' :: (FilePath -> IO a) -> Key -> Annex a
 inAnnex' a key = do
 	whenM (fromRepo Git.repoIsUrl) $
 		error "inAnnex cannot check remote repo"
-	inRepo $ a . gitAnnexLocation key
+	inRepo $ \g -> gitAnnexLocation key g >>= a
 
 {- A safer check; the key's content must not only be present, but
  - is not in the process of being removed. -}
@@ -70,7 +70,7 @@ inAnnexSafe = inAnnex' $ \f -> openForLock f False >>= check
  - it. (If the content is not present, no locking is done.) -}
 lockContent :: Key -> Annex a -> Annex a
 lockContent key a = do
-	file <- fromRepo $ gitAnnexLocation key
+	file <- inRepo $ gitAnnexLocation key
 	bracketIO (openForLock file True >>= lock) unlock a
 	where
 		lock Nothing = return Nothing
@@ -100,9 +100,8 @@ calcGitLink :: FilePath -> Key -> Annex FilePath
 calcGitLink file key = do
 	cwd <- liftIO getCurrentDirectory
 	let absfile = fromMaybe whoops $ absNormPath cwd file
-	top <- fromRepo Git.workTree
-	return $ relPathDirToFile (parentDir absfile) 
-			top </> ".git" </> annexLocation key
+	loc <- inRepo $ gitAnnexLocation key
+	return $ relPathDirToFile (parentDir absfile) loc
 	where
 		whoops = error $ "unable to normalize " ++ file
 
@@ -213,7 +212,7 @@ checkDiskSpace' adjustment key = do
  -}
 moveAnnex :: Key -> FilePath -> Annex ()
 moveAnnex key src = do
-	dest <- fromRepo $ gitAnnexLocation key
+	dest <- inRepo $ gitAnnexLocation key
 	let dir = parentDir dest
 	e <- liftIO $ doesFileExist dest
 	if e
@@ -227,7 +226,7 @@ moveAnnex key src = do
 
 withObjectLoc :: Key -> ((FilePath, FilePath) -> Annex a) -> Annex a
 withObjectLoc key a = do
-	file <- fromRepo $gitAnnexLocation key
+	file <- inRepo $ gitAnnexLocation key
 	let dir = parentDir file
 	a (dir, file)
 
@@ -250,7 +249,7 @@ fromAnnex key dest = withObjectLoc key $ \(dir, file) -> liftIO $ do
  - returns the file it was moved to. -}
 moveBad :: Key -> Annex FilePath
 moveBad key = do
-	src <- fromRepo $ gitAnnexLocation key
+	src <- inRepo $ gitAnnexLocation key
 	bad <- fromRepo gitAnnexBadDir
 	let dest = bad </> takeFileName src
 	liftIO $ do