Re: [PATCH v2 08/24] midx: respect 'core.multiPackIndex' when writing

> >   Side note: IMHO the "check all packs to see if there are any other
> >   bitmaps to warn about" behavior is kind of pointless, and we should
> >   consider just returning as soon as we have one. This is already
> >   somewhat the case after your midx-bitmap patches, as we will not even
> >   bother to look for a pack bitmap after finding a midx bitmap. That is
> >   a good thing, because it means you can keep pack bitmaps around for
> >   flexibility. But let's leave any changes to the pack-only behavior out
> >   of this series for simplicity.
> 
> I agree. I'd be in favor of something like
> [...patch...]

> > But we do allow an "--object-dir" option to "multi-pack-index write",
> > and I don't see any other code explicitly requiring that it be part of
> > the current repository. What I'm wondering is whether this would be
> > breaking:
> >
> >   cd $REPO/..
> >   git multi-pack-index --object-dir $REPO/.git/objects write
> >
> > or:
> >
> >   cd /some/other/repo
> >   git multi-pack-index --object-dir $REPO/.git/objects write
> >
> > The latter does seem to work, but the former segfaults (usually -- if
> > there's already a midx it is OK).
> 
> The former should work, but doesn't, because (as you pointed out to me
> in our regular weekly discussion off-list) that the "multi-pack-index"
> entry in git.c's commands array has the RUN_SETUP_GENTLY option, and
> probably should have RUN_SETUP so that we complain with die() instead of
> BUG.
> 
> And the latter will continue to work, but only if in your scenario that
> $REPO is an alternate of /some/other/repo.
> 
> I wrote a little bit more in [1] about this behavior, but the upshot is
> that we used to technically support passing *any* directory to
> `--object-dir`, including directories that didn't belong to an
> alternated repository.
> 
> And that will cease to work after the patch that [1] is in response to
> is applied. But for the reasons that I explain there, I think that is a
> sufficient outcome, because the behavior is kind of bizarre to begin
> with.