Can't cleanly delete CloudFormation stack due to circular dependency

[drj11]

(for tag v1.5.5commit abca285)

When you try and delete a stack the delete operation will eventually fail.
At the moment this is merely annoying because
the failure only leaves behind a few security groups which do not cost anything.

But the undeleted security groups do clutter up the account.

The failure is something like:

 	15:53:26 UTC+0100 	DELETE_FAILED 	AWS::EC2::SecurityGroup 	ELBSecurityGroup 	resource sg-9f14bae0 has a dependent object

this happens because some of the security groups have circular dependencies (these circular dependencies were added in #1606 ).

While CloudFormation can create security groups with circular dependencies, apparently it can't delete them.

As a workaround I've tried deleting the egress rules from a security group by hand and trying the delete again.
It's take uncharacteristically long, even by CloudFormation standards.

[hackdna]

I might have seen this once but I was able to delete several stacks without issues. I think it's a transient error.

[drj11]

Think you're right. Transient. Closing.