We need a final build of fedora-repos and fedora-release, for Fedora 28. The fedora-repos build must disable updates-testing by default, and the fedora-release build has to have a release of 1 or higher to disable the installer 'timbuktu' live warnings in some circumstances (IIRC). Not sure what other changes are needed, there should be an SOP.
This is a Final blocker per criterion "A fedora-release package containing the correct names, information and repository configuration for a final Fedora release must be present on release-blocking images and the appropriately versioned generic-release package must be available in the release repository."
Note there is already an update: https://bodhi.fedoraproject.org/updates/FEDORA-2018-58afdbfb7a
fedora-release-28-1 fedora-repos-28-1 has been submitted as an update to Fedora 28. https://bodhi.fedoraproject.org/updates/FEDORA-2018-58afdbfb7a
fedora-release-28-1, fedora-repos-28-1 has been pushed to the Fedora 28 stable repository. If problems still persist, please make note of it in this bug report.