euca-authorize invalid protocol yields unknown error

To reproduce:

$ euca-authorize -P tcpf -p 224 default -s 0.0.0.0/0

Expected:

Error informing me that tcpf is an invalid protocol, ideally also hinting with a list of valid protocols

Actual:

$ euca-authorize -P tcpf -p 224 default -s 0.0.0.0/0
UnknownError: An unknown error has occurred. Please try your request again.

2012-03-16 23:01:53 ERROR nova.api.ec2 [req-475d0ed1-e037-4c92-a163-0a483dfe8000 b399a42284c4438db639d41fc2530baa c4ab6c17bc4742298838bd9c6fbc41e1] Unexpected error raised: Invalid IP protocol tcpf.
(nova.api.ec2): TRACE: Traceback (most recent call last):
(nova.api.ec2): TRACE: File "/opt/stack/nova/nova/api/ec2/__init__.py", line 582, in __call__
(nova.api.ec2): TRACE: result = api_request.invoke(context)
(nova.api.ec2): TRACE: File "/opt/stack/nova/nova/api/ec2/apirequest.py", line 81, in invoke
(nova.api.ec2): TRACE: result = method(context, **args)
(nova.api.ec2): TRACE: File "/opt/stack/nova/nova/api/ec2/cloud.py", line 715, in authorize_security_group_ingress
(nova.api.ec2): TRACE: rulesvalues = self._rule_args_to_dict(context, values)
(nova.api.ec2): TRACE: File "/opt/stack/nova/nova/api/ec2/cloud.py", line 482, in _rule_args_to_dict
(nova.api.ec2): TRACE: rule = self._rule_dict_last_step(context, **kwargs)
(nova.api.ec2): TRACE: File "/opt/stack/nova/nova/api/ec2/cloud.py", line 586, in _rule_dict_last_step
(nova.api.ec2): TRACE: raise exception.InvalidIpProtocol(protocol=ip_protocol)
(nova.api.ec2): TRACE: InvalidIpProtocol: Invalid IP protocol tcpf.
(nova.api.ec2): TRACE: