Patching this behaviour should be relatively straightforward - Python 3.5 currently makes this call in non-blocking mode and falls back to reading /dev/urandom directly in that case, so we'd just be forward porting the same logic to 3.6 and raising an exception instead of falling back to the file descriptor.
Accordingly, what I propose we do is as follows:
1. Raise the concern in the F26 system-wide change proposal for migrating to Python 3.6
2. Apply the patch when the 3.6 beta releases are added to Fedora Rawhide
3. Decide whether or not to keep the patch based on ABRT results and other feedback on the Rawhide builds.
Note that if the feedback on Rawhide shows that the change is helping people to find and diagnose VMs and hardware with improperly seeded entropy pools, that's a *good* thing: this proposed change is replacing Python 3.5's "/dev/urandom and os.urandom() may silently return statistically less-than-fully-random random numbers if the kernel entropy pool isn't seeded properly" with "os.urandom() will fail noisily in those cases, so you can either switch to the random module, or fix your entropy pool seeding".