First load the ca-certificates extension. Note that the following base scripts don't support https mirrors at the moment:
- provides.sh (it will download the provides list the first time but never again)
- tce-status (only the -o switch)
- tce-update (it does still work, but will make a lot of errors while you use it)
I have some modified versions of those scripts at
https://github.com/mbartlett21/Core-scripts/blob/mjb/https that do fix the support.