Backport patch for sysctl.d handling
    
    This was required before by just
    
    https://github.com/coreos/coreos-assembler/pull/128
    
    which could wait.
    
    But now this showed up in the machine-config-operator as well:
    
    https://github.com/openshift/machine-config-operator/pull/123
    
    So let's just backport it now to make sure the new installer doesn't get
    bitten by this.