As discussed in the Liberty Design Summit "Moving apps to Python 3"
cross-project workshop, the way forward in the near future is to
switch to the pure-python PyMySQL library as a default.
https://etherpad.openstack.org/p/liberty-cross-project-python3
Change-Id: I73e0fdb6eca70e7d029a40a2f6f17a7c0797a21d