horizon hangs for 1 minute if there are no compute nodes

The problem is essentially, that Horizon is unresponsive when nova-network is not available. The behavior in Folsom is different from Essex, where it worked just fine.

Setup:
- CentOS 6.3
- EPEL packages for Folsom
- Controller node without compute nodes

On Essex:
- works fine

On Folsom:
- Horizon front page loads fine
- when you submit username/password, it hangs for one minute and then finally loads. but there is a red HTML popup saying "Error: Unable to retrieve quota information."
- as long as you add a new compute node with nova-network, it starts to work just fine

Logs:
unable to retrieve service catalog with token
Traceback (most recent call last):
File "/usr/lib/python2.6/site-packages/keystoneclient/v2_0/client.py", line 135, in _extract_service_catalog
endpoint_type='adminURL')
File "/usr/lib/python2.6/site-packages/keystoneclient/service_catalog.py", line 73, in url_for
raise exceptions.EndpointNotFound('Endpoint not found.')
EndpointNotFound: Endpoint not found.
[[31;1mRecoverable error: n/a (HTTP 504)[[0m
Traceback (most recent call last):
File "/usr/lib/python2.6/site-packages/horizon/usage/base.py", line 110, in get_quotas
self.quotas = api.nova.tenant_quota_usages(self.request)
File "/usr/lib/python2.6/site-packages/horizon/utils/memoized.py", line 33, in _call_
value = self.func(*args)
File "/usr/lib/python2.6/site-packages/horizon/api/nova.py", line 428, in tenant_quota_usages
floating_ips = tenant_floating_ip_list(request)
File "/usr/lib/python2.6/site-packages/horizon/api/nova.py", line 252, in tenant_floating_ip_list
return novaclient(request).floating_ips.list()
File "/usr/lib/python2.6/site-packages/novaclient/v1_1/floating_ips.py", line 35, in list
return self._list("/os-floating-ips", "floating_ips")
File "/usr/lib/python2.6/site-packages/novaclient/base.py", line 62, in _list
_resp, body = self.api.client.get(url)
File "/usr/lib/python2.6/site-packages/novaclient/client.py", line 239, in get
return self._cs_request(url, 'GET', **kwargs)
File "/usr/lib/python2.6/site-packages/novaclient/client.py", line 226, in _cs_request
**kwargs)
File "/usr/lib/python2.6/site-packages/novaclient/client.py", line 208, in _time_request
resp, body = self.request(url, method, **kwargs)
File "/usr/lib/python2.6/site-packages/novaclient/client.py", line 202, in request
raise exceptions.from_response(resp, body)
ClientException: n/a (HTTP 504)