Use lower case hash directories for storing files on crippled filesystems, same as is already done for bare repositories.

* since this is a crippled filesystem anyway, git-annex doesn't use
  symlinks on it
* so there's no reason to use the mixed case hash directories that we're
  stuck using to avoid breaking everyone's symlinks to the content
* so we can do what is already done for all bare repos, and make non-bare
  repos on crippled filesystems use the all-lower case hash directories
* which are, happily, all 3 letters long, so they cannot conflict with
  mixed case hash directories
* so I was able to 100% fix this and even resuming `git annex add` in the
  test case will recover and it will all just work.

Command/Unlock.hs

@@ -35,7 +35,7 @@ perform dest key = do
 	unlessM (inAnnex key) $ error "content not present"
 	unlessM (checkDiskSpace Nothing key 0) $ error "cannot unlock"
 
-	src <- inRepo $ gitAnnexLocation key
+	src <- calcRepo $ gitAnnexLocation key
 	tmpdest <- fromRepo $ gitAnnexTmpLocation key
 	liftIO $ createDirectoryIfMissing True (parentDir tmpdest)
 	showAction "copying"