As we can see in
9537453586
:
CN used to be without whitespaces around the `=` but OpenSSL 1.1 introduced
whitespaces:
1.0.1: subject=/CN=example.com
1.1.0: subject=CN = example.com
This commit makes them optional.
OpenSSL 1.1 is present on the newly-released Debian Stretch, so absence
of this fix makes us not being able to use this module on this distro.