Trying to compile Python 3.5 on Linux Mint 19, getting compiler warnings and failing tests

[Marcin G]

Hmm. From looking at your full log (THANK YOU for posting that, btw -
so many people don't), it looks like an issue with certificate
checking. Might be a bug in the test itself. Does the same thing
happen with a more recent Python build? It could be a weirdness with
specific versions of OpenSSL.

Hmm, my Googling brought me this:

https://bugs.python.org/issue30714

Apparently, the test fails with newer versions of openssl and the test was fixed in 3.7, 3.6 and 2.7, but for some reason 3.5 was removed from the versions field of this bug report.