I had the same issue with installing OpenVPN and it hangs at openvpn.postinst. My 17.10 was a fresh install in October, not upgraded from 17.04.
'plymouth --ping' seems to be the root of the problem. I had to 'kill -9' three (!) times.
Since it was asked above, I attach the result of 'ps fauxw'.
I had the same issue with installing OpenVPN and it hangs at openvpn.postinst.
My 17.10 was a fresh install in October, not upgraded from 17.04.
'plymouth --ping' seems to be the root of the problem. I had to 'kill -9' three (!) times.
Since it was asked above, I attach the result of 'ps fauxw'.