Bug#993362: cloud.debian.org: cloud-init doesnt run dhclient for IPv6

[Anton Scharnowski <ans@artfiles.de>]

Package: cloud.debian.org
Severity: important

Dear Maintainer,
the bullseye cloud image doesnt run the dhclient for IPv6.

The interfaces are configured correctly, but dhclient is only executed
for IPv4.

>> dhclient -4 -v -i -pf /run/dhclient.ens3.pid -lf /var/lib/dhcp/dhclient.ens3.leases -I -df /var/lib/dhcp/dhclient6.ens3.leases ens3

On buster on the other hand:
>> Tue Aug 31 08:56:08 UTC 2021 - dhclient run with params -4 -v -i -pf /run/dhclient.eth0.pid -lf /var/lib/dhcp/dhclient.eth0.leases -I -df /var/lib/dhcp/dhclient6.eth0.leases eth0
>> Tue Aug 31 08:56:10 UTC 2021 - dhclient run with params -6 -v -pf /run/dhclient6.eth0.pid -lf /var/lib/dhcp/dhclient6.eth0.leases -I -df /var/lib/dhcp/dhclient.eth0.leases eth0

is the dhclient executed for IPv4 and IPv6.

We run an OpenStack platform. The Issue leads to no IPv6 capabilty on the VM until you manually execute a DHCPv6 request.
The tests were conducted on a freshly initialized instance with no prior modification.