Re: git clone fails when using --dissociate together with a reference repository that contains a commit-graph

[Jeff King <peff@peff.net>]

On Tue, May 12, 2026 at 09:35:49AM +0200, Daniel Mach wrote:

> I've stumbled upon a bug that the following command failed:
> 
> $ git clone <url> <dir> --reference <old-dir> --dissociate
> fatal: unable to parse commit <SHA>
> warning: Clone succeeded, but checkout failed.
> You can inspect what was checked out with 'git status'
> and retry with 'git restore --source=HEAD :/'
> 
> Omitting --dissociate fixed the error, but it wasn't clear to me what might
> be the root cause.

I think this is the same bug discussed here:

  https://lore.kernel.org/git/20260504095110.GA599780@coredump.intra.peff.net/

I haven't worked up a more polished patch yet because I was trying to
decide between the approach given there (to lazily fall back to manual
parsing) versus filling in all of the dependent tree fields when closing
the commit-graph. Which one is cheaper depends on the access patterns
(how many commits will actually be looked at post-close, versus how many
were ever loaded).

-Peff