Hi,
Just to let all Projects using CI that our monitoring complained a lot about "flapping" connectivity to some external nodes, including github.com. After some investigations, it seems that there are some peering issues (or routing) at Level3, but errors come and go.
We can't do anything but report internally and see if then error can be reported "upstream" at the link provider level.
So this message is more about the fact that if your tests are having issues with some external connectivity, that can be related to that issue.