sageRegina: Mac OS, SageMath, and SSL

Symptom

If you receive this message

pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.

when running

sage -pip install sageRegina

it is because SageMath when installed on Mac OS X version 10.12 or later does not support SSL anymore.

Fix

You can install the necessary SSL libraries according to sage-support as follows:

sage -i openssl sage -f python2 sage -pip install sageRegina

This appears to be broken though under Mac OS Sierra (10.12.1) and Xcode 8.2.1 with Sage 7.4 and 7.5.1 (fixed though in Sage 7.6). Thanks to Saul Schleimer for reporting this. See discussion.
And many thanks to Apple for making our lives more complicated by breaking C header files! We still love you, just much less.

Background

Versions 10.12 and later of Mac OS X no longer ship with OpenSSL and SageMath does not by default include OpenSSL since the OpenSSL license is ``incompatible'' with GPL. Unfortunately, that makes it rather painful to install packages with pip. Hopefully, the maintainers of OpenSSL will soon be able to change the license to something compatible with GPL.