f3f74c5 copr-keygen: don't put copr-signer to non-existing packager group

Authored and Committed by praiskup 3 years ago
    copr-keygen: don't put copr-signer to non-existing packager group
    
    The 'packager' group looks like it never existed on keygen host.
    
    Fixes bug in 373773deb2f4fd6143e445b0dbc6ea347e1dcae0.