[CentOS-devel] keeping Extras in sync with Core

So right now following the instructions on: https://wiki.centos.org/Cloud/Docker results in a non-working Docker because the version in Extras hasn't been rebuilt yet, and there's a strong dependency on selinux policy.

I'm still trying to wade through the pile of virt7* repos to find something working, right now hitting a requirement on `skopeo-containers`.

In the future, can we ensure that there's a "CR" version of Extras[1] that is built at the same time, and they're all released at once?

We also need to figure out how CR interacts with the CBS content better.

[1] And ideally other things like the atomic host content, but let's start with Extras