Comment 2 for bug 1335473

Note I have an open MP against trusty to which I added this same fix:

https://code.launchpad.net/~davidpbritton/charms/trusty/apache2/avoid-regen-cert/+merge/223990

Even though this won't be needed as trusty has the python-pyasn1-modules package, I felt it best to include it to keep the branches in sync.