Allow private builds for a public checkout
E.g. for cases when we have public code (like c9s) but private build environment (RHEL)
The checkout should be public as long as there's at least one public build. If people don't have permissions to access the private builds, the build and test information for it should not show up on the checkout page.
If there are blocking failures for the private builds but people don't have permissions to access them, we need to put up some nice message about that.