It didn't work. I still get the series of messages
Installation succeeded.
Traceback (most recent call last):
File "/opt/eff.org/certbot/venv/bin/letsencrypt", line 7, in
from certbot.main import main
File "/opt/eff.org/certbot/venv/local/lib/python2.7/dist-packages/certbot/main.py", line 9, in
import zope.component
File "/opt/eff.org/certbot/venv/local/lib/python2.7/dist-packages/zope/component/init.py", line 16, in
from zope.interface import Interface
ImportError: No module named interface
I'm exhausted and going to bed now.