Re: [PATCH] filter-branch: Fix renaming a directory in the tree-filter

> For example, if you make it the invariant that $T contains the tree that
> matches the contents of the "$tempdir/t" work tree left in the previous
> round of filter-tree (and obviously you would want to do this only
> filter_tree is in effect), the "checkout-index + clean" would become a
> proper "branch switching".
> 
> This is obviously untested, and you would need to prime $T with an empty
> tree before entering the loop (but you could cheat by initializing T with
> an empty string), but it might make the code a bit more readable than the
> current mess.  I dunno.
> 
> 	if [ "$filter_tree" ]; then
> -		git checkout-index -f -u -a ||
> -			die "Could not checkout the index"
> -		# files that $commit removed are now still in the working tree;
> -		# remove them, else they would be added again
> -		git clean -d -q -f -x
> +		git read-tree -m -u $T $commit
> 		eval "$filter_tree" < /dev/null ||
> 			die "tree filter failed: $filter_tree"
> 
> -		(
> -			git diff-index -r --name-only $commit
> -			git ls-files --others
> -		) |
> -		git update-index --add --replace --remove --stdin
> +		git add -u && git add . && T=$(git write-tree)
> 	fi