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

[Gregory Heytings]

> Then why not change that logic in minibuffer-next-completion to be 
> smarter about this?

I (and Stefan) already tried this, it doesn't seem to be feasible with a 
small and safe change.

> What you suggest is too ad-hoc-ish, and any future change to the 
> possible values of completions-header-format will risk breaking the 
> condition you propose.

I agree about the adhocishness, but I don't see how it could be done 
differently.

> Or maybe what minibuffer-next-completion does should be rethought? Why 
> does it assume that the first candidate is on the second line? what if 
> it's on the third line instead?

It does not need to be on the second line, it's only that it cannot be at 
BOB.