proxy: Fix removal of files deleted by the proxied command.

Git.Ref.headSha doesn't really work in direct mode as there's not a head,
so it was actually diffing against the empty tree and so not removing any
deleted files. Get the sha of the current branch instead, which is the same
thing Command.Sync does.

Command/Proxy.hs

@@ -41,7 +41,8 @@ start (c:ps) = liftIO . exitWith =<< ifM isDirect
   where
 	go tmp = do
 		oldref <- fromMaybe Git.Sha.emptyTree
-			<$> inRepo Git.Ref.headSha
+			<$> (inRepo . maybe Git.Ref.headSha Git.Ref.sha
+				=<< inRepo Git.Branch.currentUnsafe)
 		
 		setuptmpworktree tmp
 		exitcode <- proxy tmp

debian/changelog

@@ -15,6 +15,7 @@ git-annex (5.20150732) UNRELEASED; urgency=medium
   * proxy: If a non-proxied git command, such as git revert
     would normally fail because of unstaged files in the work tree,
     make the proxied command fail the same way.
+  * proxy: Fix removal of files deleted by the proxied command.
 
  -- Joey Hess <id@joeyh.name>  Fri, 31 Jul 2015 12:31:39 -0400