We need a more recent version of python-requests (2.4.2) on trusty to run the debmonitor-client. Some of the remaining trusty hosts use the Ubuntu Cloud Archive which has 2.9.1 but that repository is not suitable for the non-OpenStack hosts (ships lots of modified packages without security support e.g.).
I've checked the installation status and we don't have any reverse dependencies of python3-requests installed on trusty hosts not running the Cloud Archive yet. As such, I'll backport the jessie version of python-requests (2.4.3) to trusty-wikimedia