The /etc/sysconfig/[dhcpd|dhcpd6|dhcrelay] files used for specifying the user's 
customization arguments are deprecated in Red Hat Enterprise Linux 7. Instead, these arguments can
be specified in the [dhcpd|dhcpd6|dhcrelay].service files on the "ExecStart" line.

The specified arguments are automatically moved from the /etc/sysconfig/*
files into the *.service files during upgrade. Verify that they are moved
correctly and everything works as expected.

