Comment 42 for bug 1176046

Installing isc-dhcp-client-noddns on Trusty and then upgrade to Xenial with a local archive of a modified Xenial's isc-dhcp-client to replace isc-dhcp-client-noddns package to isc-dhcp-client during release upgrade from Trusty to Xenial work as expected with a completed successful release upgrade.

+Replaces:
+ isc-dhcp-client-noddns (<< 4.2.4-7ubuntu12.8+noddnsbuild1),

Capture after upgrade :

# cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=16.04
DISTRIB_CODENAME=xenial
DISTRIB_DESCRIPTION="Ubuntu 16.04.1 LTS"

# dpkg -l | grep -i dhcp
ii isc-dhcp-client 4.3.3-5ubuntu12.7 amd64 DHCP client for automatically obtaining an IP address
rc isc-dhcp-client-noddns 4.2.4-7ubuntu12.8+noddnsbuild1 amd64 Dynamic DNS (DDNS) enabled DHCP client
ii isc-dhcp-common 4.3.3-5ubuntu12.6 amd64 common files used by all of the isc-dhcp packages

# lsof -i udp
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
dhclient 707 root 6u IPv4 16437 0t0 UDP *:bootpc

# ls -altr /sbin/dhclient*
-rwxr-xr-x 1 root root 15219 Jan 11 09:12 /sbin/dhclient-script
-rwxr-xr-x 1 root root 487248 Jan 11 09:12 /sbin/dhclient

The only thing that could be improve that I can't think of right now, is to not make isc-dhcp-client-noddns not turn into "rc" state by making sure its configuration files doesn't remain.

- Eric