Re: [PATCH] Add git-filter-branch

[Johannes Sixt <J.Sixt@eudaptics.com>]

Johannes Schindelin wrote:
> 
> This script is derived from Pasky's cg-admin-rewritehist.
> 
> In fact, it _is_ the same script, minimally adapted to work without cogito.
> It _should_ be able to perform the same tasks, even if only relying on
> core-git programs.
> 
> All the work is Pasky's, just the adaption is mine.
> 
> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> Hopefully-signed-off-by: Petr "cogito master" Baudis <pasky@suse.cz>

If you hadn't done that, I'd done it sooner or later. Thanks!

> +       -r)
> +               unchanged="$(get_parents "$OPTARG") $unchanged"
> +               ;;
> +       -k)
> +               unchanged="$(git-rev-parse "$OPTARG"^{commit}) $unchanged"
> +               ;;

These two (-r and -k) together with...

> +# seed with identity mappings for the parents where we start off
> +for commit in $unchanged; do
> +       echo $commit > ../map/$commit
> +done

... this and ...

> +               if [ -r "../map/$parent" ]; then
> +                       for reparent in $(cat "../map/$parent"); do
> +                               parentstr="$parentstr -p $reparent"
> +                       done
> +               else
> +                       die "assertion failed: parent $parent for commit $commit not found in rewritten ones"

... this, means that any simple command like 

  git filter-branch -k orgin/master origin/next new-next

of your git.git clone will fail with the "assertion failed". (I haven't
tried your script, yet, but cg-admin-rewritehist fails.)

I propose that you just get rid of the "seed" stance and don't fail if a
commit cannot be mapped - just use it unchanged (don't forget to adjust
the map() function, too). Then you can get rid of -r and use -k to
specify everything you want under "--not" in the rev-list.

-- Hannes