Also, add a conflict for older versions of 'redhat-release'. Using
  them would cause unbootable system most likely...

  This is complete rework of how we generate the /etc/resolv.conf.

  Fixes:
   * always update 'nameserver' & 'search' entries when DNS* & DOMAIN
     options (respectively) were updated in ifcfg-* files
   * always update the order of 'nameserver' entries when the order of
     DNS* options was updated

  Enhancements:
   * added support for DNS3 option (equals to MAXNS value in GLIBC)
   * added logic to process duplicate DNS* options
   * added logic to process randomly omitted DNS* options (e.g. omitting
     DNS1 while specifying DNS2 and/or DNS3 will still work now)

  This work was based on these two RHEL-7.5 BZs:
  https://bugzilla.redhat.com/show_bug.cgi?id=1364895
  https://bugzilla.redhat.com/show_bug.cgi?id=1357658

  The symlinks are no longer needed. Enablement of default services
  is now managed by 'redhat-release' package.

  Resolves: #1395391
  Resolves: #1357648

  Otherwise obtaining IP from DHCP might fail. Based on patch from:
   * Rich Alloway <richard.alloway@roguewave.com> | CentOS BZ #0011138

  And network-scripts/network-functions was patched to use convert2sec().

  This function can be used to convert the value of its first parameter
  to a number of seconds - based on the time unit (specified as the
  second parameter).

  This is mostly useful for converting values for use with the sleep(1).

  In some cases we are using "on" or "off" as values. is_true()
  and is_false() can be used for evaluation of these values as well.

  The time units had to be manually converted from microseconds to
  seconds. Hopefully this was done right.