Re: [PATCH 1/2] ref-filter: refactor do_merge_filter()

> One thing that this commit message lacks is a high-level explanation
> of why these changes are being made. One possible rewrite would be:
>
>     ref-filter: make internal reachable-filter API more precise
>
>     The internal reachable-filter API is a bit loose and imprecise; it
>     also bleeds unnecessarily into the public header. Tighten the API
>     by:
>
>     * renaming do_merge_filter() to reach_filter()
>
>     * separating parameters to explicitly identify what data is used
>       by the function instead of passing an entire ref_filter_cbdata
>       struct
>
>     * renaming and moving internal constants from header to source
>       file

>> +static void reach_filter(struct ref_array *array,
>> +                        struct commit_list *check_reachable,
>> +                        int include_reached)
>>  {
>>         [...]
>> +       if (!check_reachable)
>>                 return;
>
> I would probably drop this conditional return altogether ...