Comment 6 for bug 1749244

We ran into the same issue in our infrastructure. Valuable hint was the following entry in the debug output of tox: "GET http://no.where/v2.0" - which resulted in a 200 OK response. On a local system this was not the case as "no.where" should not resolve to anything and the unit test actually expects an error instead of a successful connection here.

However, in our case a DNS server was the culprit, which still resolved the name to an internal address. When executing "dig http://no.where/v2.0" on the system running the unit tests, we saw a DNS answer. Removing the DNS resolution for "no.where" solved the issue.

So, maybe check the DNS resolution on your CI systems!