Re: [PATCH] transplant: move a series of commits to a different parent

[Alex Riesen <raa.lkml@gmail.com>]

Steffen Prohaska, Sun, Jun 24, 2007 19:13:42 +0200:
> >>I am changing the repository.
> >
> >No, you don't.
> 
> Magically, the script solved my problem by creating a new, corrected
> branch that is different from the original one. I didn't run any
> other script. I promise, I ran the script that I sent in the patch.

I meant: "it does not change the working directory". It is irrelevant,
was a bit of confusion on my part.

Your script works, just it can be made simplier: no need for diff,
it'll only hurt perfomance and complicates things. And you don't have
to care about additions/deletions, and it is trivially extensible to
support merges, and the current index is untouched - your user can
continue working in predictable environment.

As to perfomance: read-tree doesn't actually _read_ the blobs to
populate index, just the trees. And diff-tree has do do the same, but
also _compare_ two trees recursively: more work, more memory needed.

BTW, Johannes moved that ident code you copied from git-filter-branch
into its own shell file, so it can be sourced and trivially reused.