WDYM by 4GB size limit? When I run du -h on my linux checkout, I get 6.4G (no build artifacts, just git tracked source code plus the .git directory). Even if I only look at the .git/objects directory, it's 5.2G large.
Chromium is also well over the size limit.
That makes sense for GitHub, because what they really care about is the hard drive space you use up, and a repo containing a commit they are already storing for some large project is no additional disk space.