lxc 'unset' can be used to set config key:value

Using "$ lxc <entity> unset <entity> <key>"

If a value is passed in after the key the config key will be set with the value passed in.

"$ lxc <entity> unset <entity> <key> <value>" behaves as you would expect "$ lxc <entity> set <entity> <key> <value>" to behave.

The cli parser does not complain about an incorrect number of parameters.

Examples and OS/LXD version info below

ubuntu@FF00:~$ lxc network unset br1 bridge.external_interfaces enp7s0f0
ubuntu@FF00:~$ lxc network show br1
config:
  bridge.external_interfaces: enp7s0f0
  ipv4.address: 172.17.1.2/24
  ipv4.nat: "false"
  ipv6.address: none
name: br1
type: bridge
used_by:
- /1.0/containers/enabled-possum
managed: true

ubuntu@FF00:~$ lxc network unset br1 bridge.external_interfaces garbage
ubuntu@FF00:~$ lxc network show br1
config:
  bridge.external_interfaces: garbage
  ipv4.address: 172.17.1.2/24
  ipv4.nat: "false"
  ipv6.address: none
name: br1
type: bridge
used_by:
- /1.0/containers/enabled-possum
managed: true

ubuntu@FF00:~$ lxc network unset br1 bridge.external_interfaces
ubuntu@FF00:~$ lxc network show br1
config:
  ipv4.address: 172.17.1.2/24
  ipv4.nat: "false"
  ipv6.address: none
name: br1
type: bridge
used_by:
- /1.0/containers/enabled-possum
managed: true

ubuntu@FF00:~$ lxc profile set default limits.memory 10GB
ubuntu@FF00:~$ lxc profile show default
config:
  limits.memory: 10GB
description: Default LXD profile
devices:
  eth0:
    nictype: bridged
    parent: br1
    type: nic
  root:
    path: /
    pool: default
    type: disk
name: default
used_by:
- /1.0/containers/enabled-possum

ubuntu@FF00:~$ lxc profile unset default limits.memory 5GB
ubuntu@FF00:~$ lxc profile show default
config:
  limits.memory: 5GB
description: Default LXD profile
devices:
  eth0:
    nictype: bridged
    parent: br1
    type: nic
  root:
    path: /
    pool: default
    type: disk
name: default
used_by:
- /1.0/containers/enabled-possum

ubuntu@FF00:~$ lxc profile unset default limits.memory
ubuntu@FF00:~$ lxc profile show default
config: {}
description: Default LXD profile
devices:
  eth0:
    nictype: bridged
    parent: br1
    type: nic
  root:
    path: /
    pool: default
    type: disk
name: default
used_by:
- /1.0/containers/enabled-possum

ubuntu@FF00:~$ uname -a
Linux FF00 4.4.0-65-generic #86-Ubuntu SMP Thu Feb 23 17:49:58 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

ubuntu@FF00:~$ lsb_release -rd
Description: Ubuntu 16.04.2 LTS
Release: 16.04

ubuntu@FF00:~$ lxc version
2.10.1

ubuntu@FF00:~$ apt list --installed | grep lxd

lxd/xenial,now 2.10.1-0ubuntu1~ubuntu16.04.1~ppa1 amd64 [installed]
lxd-client/xenial,now 2.10.1-0ubuntu1~ubuntu16.04.1~ppa1 amd64 [installed]
lxd-tools/xenial,now 2.10.1-0ubuntu1~ubuntu16.04.1~ppa1 amd64 [installed]