Agent 6.0 can't update policies from Rudder 5.0
Related to #16576.
Here, the problem seems to be that generation is not able to find the cfengine key even if present:
[2020-04-08 12:06:22] INFO policy.generation - Node 'agent.rudder.local' (ce6cd53a-ee9b-4c95-aff4-6277809e40e1) has an unsuported key type (CFEngine agent with certificate?) and a we do not know how to generate a hash yet