'Determine reposync command'

def reposync_cmd(self):

    cmd = None
    if os.path.exists('/usr/bin/dnf'):
        cmd = '/usr/bin/dnf    reposync'
    elif os.path.exists('/usr/bin/reposync'):
        cmd = '/usr/bin/reposync'
    else:
        utils.die(self.logger, 'no    /usr/bin/reposync    found,    please    install    yum-utils')
    return cmd
