Does this work?

*** New user option 'vc-hg-revert-switches' specifies switches to pass
to hg revert.

On February 4, 2019 11:54:03 AM EST, Eli Zaretskii <eliz@gnu.org> wrote:
>> From: Ian Dunn <dunni@gnu.org>
>> Date: Sun, 03 Feb 2019 21:55:50 -0500
>> 
>> * vc/vc-hg.el (vc-hg-revert-switches): New user variable.
>>   (vc-hg-revert): Use switches for revert.
>
>Thanks.  Please also include an announcement of this in NEWS.

-- 
Ian Dunn