It normally depends on pyopenssl but when USE=test is set, it wants openssl
Did you test it against libressl? I don't have an install handy.
Created attachment 588614 [details] ndg-httpsclient-0.4.2-r1:20190831-205451.log libressl_failed_tests
I forced the install and it fails some tests see attachment
In that case, either pyopenssl or this package needs patching.
Should I open another bug for the failures?