bug#60411: 29.0.60; minibuffer-next-completion skips first candidate when completions-header-format and completion-show-help are nil

[Eli Zaretskii]

> Cc: 60411@debbugs.gnu.org
> Date: Sat, 31 Dec 2022 15:02:57 +0000
> From: Gregory Heytings <gregory@heytings.org>
> 
> > For completeness, you may consider also handling the case where 
> > completions-header-format is an empty string, which is another not too 
> > unreasonable way to disable the header. minibuffer-next-completion still 
> > skips the first candidate for that case.
> >
> 
> Thanks for your feedback!  Indeed, that's another bug, which makes a fix 
> elsewhere in the code even less likely.  It is fixed in the attached 
> patch.  Can you try it?
> 
> Eli, do you have objections to that patch?

It becomes less and less to my liking, TBH: too much ad-hocery.  Juri,
Stefan, WDYT? is this safe enough for the release branch?