j2kun seems to be a googler so I don't think so, but it's true that Facebook also went with Mercurial. I suspect it was for similar reasons.

Ahh. It sounded like a repeat of https://graphite.dev/blog/why-facebook-doesnt-use-git but maybe it did happen for both companies! They’d obviously be having similar issues. Thanks :)

I can second that the aforementioned reasons are true. The funny difference is that Google employs the primary git maintainer. Git has a lot of customers though so it rightfully is very conservative with development.