For some strange reason whenever I wanted to download python-dateutil I am using the owner's mirror - this was true a couple months ago, not sure if this is still the case and because we run CI on a remote service we used to get package not available because labix couldn't serve the content. This is just a side note but does PYPI has a resolution to enforce all package author to serve package from pypi mirrors?

and I never knew about the extra option in pip. Cool update btw.