> Go was on Mercurial before so it was already away from any Google own source control system.

How being on Mercurial implies that it was "away from Google code" ? It is in fact hosted on Google code currently (https://code.google.com/p/go/)

PS: Google code supports: subversion, mercurial and even git (https://code.google.com/p/support/wiki/GettingStarted#Workin...)

I think he meant that it wasn't on their internal source control system, which is one massive repo.