The wheels currently built for Striker work on Trusty but do not work on stretch. For example:
cffi-1.7.0-cp34-cp34m-linux_x86_64.whl is not a supported wheel on this platform.
So, everything for striker needs to be rebuilt on a Stretch build hosts. I'm not sure how best to ensure co-existence between this new Stretch build and the existing, running Trusty build.
The simplest approach is to just freeze the current Californium build of Striker, pull Californium out of the dsh install list for striker, and move to Stretch all at once. Otherwise I guess we need to branch the Striker deploy source, and also have two different deploy setups on Tin.