Some organizations return a 5xx error

Reported by @se7entyse7en 

It seems that the problem is the library used to discover repositories:

https://github.com/google/go-github/issues/999

Organization `src-d` works but others like `google` or `jenkinsci` doesn't. Maybe using an old version solves the problem:

https://github.com/google/go-github/commit/d20deacea658223895efa3600c28053e733a512f