FailedVariableLookup: Couldn't resolve lookups in variable `Cluster`

We recently tried upgrading stacker and got an error:
```
[2018-05-15T15:28:22] ERROR production-bot-refresh-service stacker.plan:92(_run_once): Got unexpected keyword argument 'retries'
Traceback (most recent call last):
File "/Users/jamie/.pyenv/versions/2.7.11/lib/python2.7/site-packages/stacker/plan.py", line 88, in _run_once
status = self.fn(self.stack, status=self.status)
File "/Users/jamie/.pyenv/versions/2.7.11/lib/python2.7/site-packages/stacker/actions/diff.py", line 216, in _diff_stack
provider_stack = self.provider.get_stack(stack.fqn)
File "/Users/jamie/.pyenv/versions/2.7.11/lib/python2.7/site-packages/stacker/providers/aws/default.py", line 489, in get_stack
return self.cloudformation.describe_stacks(
File "/Users/jamie/.pyenv/versions/2.7.11/lib/python2.7/site-packages/stacker/providers/aws/default.py", line 478, in cloudformation
max_attempts=MAX_ATTEMPTS
File "/Users/jamie/.pyenv/versions/2.7.11/lib/python2.7/site-packages/botocore/config.py", line 94, in __init__
args, kwargs)
File "/Users/jamie/.pyenv/versions/2.7.11/lib/python2.7/site-packages/botocore/config.py", line 119, in _record_user_provided_options
'Got unexpected keyword argument \'%s\'' % key)
TypeError: Got unexpected keyword argument 'retries'
[2018-05-15T15:28:22] DEBUG production-bot-refresh-service stacker.plan:148(set_status): Setting bot-refresh-service state to failed.
[2018-05-15T15:28:22] INFO production-bot-refresh-service stacker.ui:36(info): production-bot-refresh-service: failed (Got unexpected keyword argument 'retries')
[2018-05-15T15:28:22] ERROR MainThread stacker.actions.base:198(execute): The following stacks failed: production-bot-refresh-service
```

We were on version 1.0.4 previously and tried upgrading to 1.2.* (I initially tried going to 1.3.* but got the same error and narrowed it down to the 1.2.* upgrade).

I haven't changed anything else (e.g. blueprints, stack config, etc.) so it's very possible that it's a backwards compatibility issue. It's just hard to debug since the error is not very helpful.

Any insight would be appreciated. I'd like to upgrade to the latest stacker (and also troposphere) so that we can add support for some new AWS properties.