The dhcp6relay rules file had a line overwriting a variable for
docker-dhcp-relay. Remove that line.
This line caused a limited impact where if some (many?) of the docker
containers were already built, except for dhcp-relay, and the build
failed or was interrupted, then dhcp-relay container would fail to build
because this variable was overwritten and the python3-swsscommon
wouldn't get installed into the slave container. Most builds would be
fine, though.
Signed-off-by: Saikrishna Arcot <sarcot@microsoft.com>
