ipapython.ipautil.nolog_replace: Do not replace empty value
    
    When provided empty value in nolog parameter nolog_replace added 'XXXXXXXX'
    three (once for plain value, once for http quoted value and last time for shell
    quoted value) times before every character (including terminating '\0') in the string.
    
    https://pagure.io/freeipa/issue/6738
    
    Reviewed-By: Pavel Vomacka <pvomacka@redhat.com>