bug#57807: 29.0.50; Make vc-print-branch-log able to log multiple branches

[Juri Linkov]

>>> I'm running into the problem that you pointed out in another thread.
>>> How do we apply vc-filter-command-function to the final VC command
>>> that's to be run without also applying it to intermediate VC commands,
>>> e.g. in vc-read-revision?
>>
>> Maybe there is no problem to apply the editing filter to all commands,
>> I don't know.  First need to try to see how it really works.
>
> Here's the WIP patch, hopefully it works well enough for testing.

Thanks, I'm going to try it out.

> I think it's considerably worse than C-u C-x v b l tbh.

Undoubtedly, it's worse.  But it solves the problem that
all vc commands can't use C-u.