2d962c9 Change the ArtifactBuild.rebuilt_nvr when retrying failed build.

Authored and Committed by jkaluza 5 years ago
    Change the ArtifactBuild.rebuilt_nvr when retrying failed build.
    
    Koji or /OSBS might be in weird state in which the build for old
    NVR already exists and rebuild would fail because of NVR conflict.