bug#40919: 27.0.91; next-error-select-buffer does not always behave as documented

[Juri Linkov]

>> It seems there is no right answer suitable for all users.  So I propose
>> to add more options.
>>
>> Eli, do you agree with adding more options to 
>> `next-error-find-buffer-function'
>> in emacs-27?
>>
>> Currently it has one option that defines one of possible behaviors existed
>> in older versions.  Now we need to add other option for compatibility
>> with pre-27 versions.
>>
>> Then users of emacs-27 could decide whether they want to keep
>> the old behavior or use the new.
>
> I think the time for adding new options to Emacs 27 has come and gone
> long ago.  We should defer that to future releases.

To do nothing in emacs-27 is one variant, indeed.  Another variant would be
to add an optional choice to the existing option that allows to restore
the old behavior and doesn't affect the current behavior in any way.
A third variant is to explain in the documentation what defadvice
the users could add to their init files to restore the old behavior.