What? I don't believe this. Git has nothing that hg devs would want, and lacks many features that hg aficionados like me love. Where did you see this move?
Wish I could find it now, it was linked to on HN between 6 and 12 months ago IIRC, it was on an issue tracker or mailing list archive. A number of the devs were in favor of moving to git, it was shot down but was an interesting discussion and appeared to be serious. Git was a better fit for some particular use case in the workflow on Hg trunk, but now the details have escaped my mind.