bug#54993: 28.1; Editing etc/NEWS on master with Emacs 28 signals an error

[Kévin Le Gouguec]

Juri Linkov <juri@linkov.net> writes:

>>> there are different outline header colors between Emacs 28 and 29
>>> because of different outline levels.  The additional level comes
>>> from the space character at the end of outline-regexp "^\\*+ ".
>>
>> I wanted to avoid having stuff like
>>
>> ** New thing for help buffers.
>> *Help* buffers can be etc...
>>
>> triggering an outline thing on the second line.  Is there a way to do
>> that without including the space in outline-regexp?
>
> I see only 1 way: to set buffer-local outline-level where to subtract 1.

FWIW, this is exactly what org-outline-level does, since Org also sets
outline-regexp to "\\*+ ".

(NB: IIUC from outline-regexp's docstring, it is not necessary to anchor
the regexp with "^")