Rich,
back in 3.10 cycle we had few issues around python-docker-py & python-docker rpms which was causing incompatibility with atomic-1.22 which in turn caused big problems with CI Origin pipeline.
As such Brian was able to fix up the [2] dependency and so we sorted it out atomic-1.22 however we have not rollback on -testing or -candidate as it too much effort to fix it hence the differences you saw.
We didn't tackle the v3.10 release since it was already out there in the field.
Saying that i don't have an alternative for you right now, will need to think a bit about it. The risk is that we might break again the CI Origin dependency chain and i'd like to avoid that
will need to think about it.
[1] https://github.com/openshift/origin/issues/20653#issuecomment-413322137
[2] http://mirror.centos.org/centos/7/paas/x86_64/openshift-origin310
[3] http://lists.openshift.redhat.com/openshift-archives/users/2018-November/msg00007.html
https://lists.centos.org/pipermail/centos-devel/2018-November/017050.html