Re: merge-base: update the clean-up postprocessing

Johannes Schindelin [off-list ref] writes:

BTW ALAS' argument about grafts not only shot down my maximumSkew, but 
AFAICT also the generation number thing. Besides, the generation number 
could be manipulated by a mean-spirited person also.

I think with the fixed-up version of "concepts only" patch,
generation number approach is already moot.