IPv6 only on the generic image doesn't work as it should

[Thomas Goirand <zigo@debian.org>]

Hi,

Currently, using the generic-cloud image (and even when switching to a 
non-cloud kernel), if using a v6only network, systemd-networkd is 
waiting forever for network to be up, when it should not, and continue 
booting.

Note that my setup is using dhcpv6, not SLAAC.

Cheers,

Thomas Goirand (zigo)