Let's Encrypt - python-dateutil brakes certbot installation (botocore dependency)

Latest upgrade of python-dateutil brakes certbot and tons of other packages relying on botocore.

An unexpected error occurred:
ContextualVersionConflict: (python-dateutil 2.7.2 (/usr/local/lib/python2.7/dist-packages), Requirement.parse('python-dateutil<2.7.0,>=2.1'), set(['botocore']))

To downgrade to the latest version less big then 2.7:

pip install "python-dateutil<2.7.0,>=2.1"

Other software affected is for example ElasticSearch Alert