Re: [PATCH 1/2] sequencer: handle empty-set cases consistently

> If the user gives us a set that prepare_revision_walk()
> takes to be empty, like:
> 
>   git cherry-pick base..base
> 
> then we report an error. It's nonsense, and there's nothing
> to pick.
> 
> But if they use revision options that later cull the list,
> like:
> 
>   git cherry-pick --author=nobody base~2..base
> 
> then we quietly create an empty todo list and return
> success.
> 
> Arguably either behavior is acceptable, but we should
> definitely be consistent about it. Reporting an error
> seems to match the original intent, which dates all the way
> back to 7e2bfd3f99 (revert: allow cherry-picking more than
> one commit, 2010-06-02). That in turn was trying to match
> the single-commit case that exited before then (and which
> continues to issue an error).
> 
> Signed-off-by: Jeff King <peff@peff.net>