Comment 8 for bug 1385276

@jam, this is leaving sec groups behind when destroying a model. Repro:

$ juju version
2.2-beta3-xenial-amd64

$ juju add-model foo aws/us-west-1
Using credential 'default' cached in controller
Added 'foo' model on aws/us-west-1 with credential 'default' for user 'admin'

$ juju deploy ubuntu -n 10
Located charm "cs:ubuntu-10".
Deploying charm "cs:ubuntu-10".

## wait for deployment to finish, take a look at the aws console, see 10 new instances/volumes and 11 new secgroups.

$ juju destroy-model foo
...
http://paste.ubuntu.com/24555130/
...

## check aws console, see 10 fewer instances/volumes, but only 1 less secgroup.

The +11 / -1 related to security groups seems strange to me. To put real numbers behind it, I had 3 secgroups before deployment, 14 after i added the ubuntu units, and 13 after destroying the model.

The result is that I have to go to aws every couple weeks and delete secgroups once i hit my limit of 500.