Thanks for info, that's helpful. It seems especially bad with virtualenv, since you have the possibility that different Python environments on the same computer have different certificate sets, depending on when you created the virtualenv or whether you updated certifi in that environment.
I think the changes should have been a lot more obvious. The OSX installer should have popped up a big box saying "Warning: This version of Python does not have any SSL certificates and will not be able to connect to secure HTTP connections. Without certificates these connections will fail to work. Please click this button to install the 'certifi' package, and read these VERY IMPORTANT notes to understand the implications of this change"
I think the changes should have been a lot more obvious. The OSX installer should have popped up a big box saying "Warning: This version of Python does not have any SSL certificates and will not be able to connect to secure HTTP connections. Without certificates these connections will fail to work. Please click this button to install the 'certifi' package, and read these VERY IMPORTANT notes to understand the implications of this change"