consensus weight case 2b3 does not follow dir-spec

dir-spec says the following.

If M > T/3, then the Wmd weight above will become negative. Set it to 0
in this case:
   Wmd = 0
   Wgd = weight_scale - Wed

The code dutifully sets Wmd to 0, but neglects Wgd.

I assume the spec is correct and the intended behavior. Branch incoming once I get a ticket number.