packager_alias: Allow for sporadic failures in retrieving info from dist-git
    
    Basically, if we fail to retrieve data from pagure or we fail to
    convert from JSON, wait for 30 seconds and retry.
    If after two minutes (4 attempts) it still hasn't worked, bail.
    
    Fixes https://pagure.io/fedora-infrastructure/issue/7603
    
    Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>