I'm running into the same issue. Using python venv I was able to get certbot working using pip.
Steps: Install virtualenv
pip install virtualenv --upgrade
Create a virtualenv
virtualenv -p /usr/bin/python2.7 certbot
Activate the certbot virtualenv
. /root/certbot/bin/activate
Your prompt might turn into something like this
(certbot) [root@hostname ~]#
Then pip install certbot
pip install certbot
Once complete you can test certbot command under the certbot virtualenv, but this is not practical if you are going to use cron to setup certbot renewals. So deactivate the virtual environment,
(certbot) [root@hostname ~]# deactivate
Now run the certbot command from
/root/certbot/bin/certbot