Using git.ruby-lang.org for non-commit purposes is discouraged. GitHub
mirror is actually recommended because it's reliable than single-hosted
git.ruby-lang.org, the mirror is almost always well-maintained, and its
latency is very small (usually about 10s).
Use GitHub ruby.git for make-snapshot
Previously @hsbt (Hiroshi SHIBATA) disabled https git clone from git.ruby-lang.org.
Using git.ruby-lang.org for non-commit purposes is discouraged. GitHub
mirror is actually recommended because it's reliable than single-hosted
git.ruby-lang.org, the mirror is almost always well-maintained, and its
latency is very small (usually about 10s).
So we should just use GitHub here.
[Bug #15969]