Earlier quoted context omitted.
Which is kind of ridiculous. If your CI breaks because GitHub is down, it means it's not caching dependencies locally, but keeps re-downloading them every time it runs (e.g. every commit), generating tons of waste and unnecessary load on the hosting service. Or, to put it bluntly, if your CI works like this, it's contributing to climate change.
That’s an excellent point. How can you tell if the CI system uses caching, other than waiting for a github outage to notice something broke?
Many CI systems provide a build log, do they not? Look for a “git fetch” in it instead of a “git clone”.