ip6=dhcp turns on ip=dhcp

[Scott Moser]

When testing bug 1639930 I found that booting a system with:
 ip6=dhcp
will enable ip=dhcp. ip= does not enable ip6=dhcp, so this is odd behavior.

Thus, if you had an ip6 only network, in order to do this you have to do:
 ip6=dhcp ip=off

This is really just a matter of a very strange behavior, but behavior that can be fixed by just explicitly passing ip=off.

Related bugs:
 * bug 1639930: initramfs network configuration ignored if only ip6= on kernel command line
 * bug 1621507: initramfs-tools configure_networking() fails to dhcp IPv6 addresses

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: initramfs-tools 0.122ubuntu8.7
ProcVersionSignature: User Name 4.4.0-53.74-generic 4.4.30
Uname: Linux 4.4.0-53-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.4
Architecture: amd64
Date: Fri Dec 16 17:06:23 2016
PackageArchitecture: all
ProcEnviron:
 TERM=vt220
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: initramfs-tools
UpgradeStatus: No upgrade log present (probably fresh install)

[LaMont Jones (lamont)]

Based on a conversation with Scott, we are both of the opinion that this bug should not delay the landing of the fixes for bug 1621507 and bug 1621615 into xenial and yakkety.