Re: [PATCH/RFD 3/6] rev-list: list all heads with --all

> HEAD is a worktree specific sysmref, so that a repository with multiple
> worktrees can have multiple HEADs, or HEADs in a worktree different from
> the current worktree.
>
> So far, "rev-parse --all" adds only the HEAD from the current worktree
> to the list of refs (besides branches etc.). So, a detached HEAD from a
> different checkout would be missed unless a shared ref (or current HEAD)
> points to it (or descents from it). As a consequence, "git prune" can
> prune detached HEADs from worktrees and leave the repo in an
> inconsistent state.
>
> Make "rev-parse --all" add the HEADs from all worktrees. This results in
> a non-worktree-specific ref list and solves the pruning problem.
>
> Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
> ---
>
> Notes:
>     This patch solves the pruning problem with worktrees, but I feel quite
>     uneasy about substituting the ref solving at the very heart of refs.c. So
>     please consider this a mere poc and a request for discussion/input
>     about how to do this the right way.
>
>     In essence, I feel the worktree interface still has to evolve a bit: I'd
>     rather for_each_worktree than loop myself, and if many call sites need to
>     be aware of multiple heads or worktrees than get_worktrees() should be
>     part of our init stuff, not here. [I may be out of sync of newer progress.]