Re: Filter-branch's "move tree to subdirectory" example fails with BSD sed?

Jeff King [off-list ref] writes:

I wish we could also get rid of the temporary index. It exists solely
for the side effect of removing the existing entries (otherwise, you get
both "foo" and "newsubdir/foo" in the resulting history). It would be
nice if there was some flag to update-index to say "before you do
anything, clear the existing index" (or I guess, "don't bother reading
the existing index"). And then result could look like:

  git filter-branch --index-filter '
    git ls-files -sz |
    perl -0pe "s{\t}{\tnewsubdir/}" |
    git update-index --from-scratch -z --index-info
  ' HEAD

which is IMHO much easier to read and understand.

Wouldn't "git read-tree --prefix=newsubdir/" suffice without the pipeline?
I.e.

        git filter-branch --index-filter '
		rm -f "$GIT_INDEX_FILE"
                git read-tree --prefix=newsubdir/ "$GIT_COMMIT"
	' HEAD