I believe that you should not restrict openscap-daemon to a specific
Python version. This is useless work that needs to be undone rather
soon since
Python 3.7 aims to be the default.
It's perfectly OK if there's a bug open for a while in unstable until
we have a fix.
If you want to go faster, you could write a Debian-specific patch
yourself
until upstream releases an update. It's usually not hard, you just have
to
rename the "async" variables/attributes in some consistent manner
everywhere. It needs some care/coordination with upstream when it's
part
of the API though (exposed attribute name in methods for example).