v7 for all repositories

* Default to v7 for new repositories.
* Automatically upgrade v5 repositories to v7.

Git/Index.hs

@@ -58,19 +58,3 @@ currentIndexFile r = fromMaybe (indexFile r) <$> getEnv indexEnv
 {- Git locks the index by creating this file. -}
 indexFileLock :: FilePath -> FilePath
 indexFileLock f = f ++ ".lock"
-
-{- When the pre-commit hook is run, and git commit has been run with
- - a file or files specified to commit, rather than committing the staged
- - index, git provides the pre-commit hook with a "false index file".
- -
- - Changes made to this index will influence the commit, but won't
- - affect the real index file.
- -
- - This detects when we're in this situation, using a heuristic, which
- - might be broken by changes to git. Any use of this should have a test
- - case to make sure it works.
- -}
-haveFalseIndex :: IO Bool
-haveFalseIndex = maybe (False) check <$> getEnv indexEnv
-  where
-	check f = "next-index" `isPrefixOf` takeFileName f