The Workstation product includes a package called "PackageKit-cached-metadata" which is just the latest repo metadata packaged up, in order to make the initial gnome-software launch faster, without having to wait for the initial metadata download. If there's going to be an RC2, it would be nice to refresh the packaged up metadata, just to make sure that it's as close as possible to the final repo metadata. I've done a new PackageKit-1.0.6-4.fc22 build with the latest F22 metadata as of today's morning. The only change there is the newer metadata and there are no code changes. The metadata doesn't have to be 100% in sync, since gnome-software is going to refresh it anyway when it's doing the first updates check, but having it as close as possible to the final repo metadata makes the initial experience (mostly on the live media where automatic metadata fetching is disabled) nicer.
PackageKit-1.0.6-4.fc22 has been submitted as an update for Fedora 22. https://admin.fedoraproject.org/updates/PackageKit-1.0.6-4.fc22
+1 FE, this is just metadata and should be safe to do. If there's outdated metadata, it causes issues for gnome-software (it would be great to make it more robust, hint hint).
+1 FE
PackageKit-1.0.6-4.fc22 has been pushed to the Fedora 22 stable repository. If problems still persist, please make note of it in this bug report.