It broke a bash script that’s going to be gone within a month. The continuous integration stack in Gentoo (which probably doesn’t do quite what you think it does) is basically a stack of bash hacks that causes as many problems as it solves, so it’s being retired. ( relevant gentoo-dev ML thread )
When I first installed Gentoo, it was because it was one of only around three distros that supported x86_64 at the time. Yes, that was a long time ago.
I’ve kept it as a daily driver for a number of reasons. First, because I’m a control freak, and Gentoo goes out of its way to allow me to select exactly the packages I want, and gives me access to all the knobs and switches that other distros may hide in the name of user-friendliness.
Second, because once installed it’s surprisingly solid and trouble-free—Portage is an excellent (if slow) package manager that, judging from what I’ve heard from people running other distros, is better than the average at preventing breakage, and since it’s rolling-release there are no whole-distro upgrades to complicate things. I ran one system on rolling updates for 17 years without reinstalling, and it was still pretty much up-to-date on all packages when I retired it back in March—try that with Ubuntu. (The replacement system also runs Gentoo.)
Thirdly, I’ve been with Gentoo for so long that I know how to create packages, unbork a system that I’ve messed up by doing something really stupid, and various other tricks. If I went to another distro, I’d have to relearn much of that from scratch.
(A fourth reason for some might be that it supports a wider range of CPU architectures than any other distro except possibly Debian.)
Github is only used to mirror the main repo (which is on gitweb.gentoo.org). I assume that was done to attract driveby patches and reduce load from Portage git syncs on the Gentoo servers.