Comment by sangnoir

> Facebook didn't use mercurial because of big O, they used it because of hubris and a bad disk config.

Half-remembering a blog post I read - the git maintainers also wouldn't give Facebook the time of day on code changes to accommodate FBs requirements. Mercurial was more amenable. This also disproves the "Facebook has a fork of evertyhing, because the attempted to upstream the changes they wanted)