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Hi guys.
Recently, I've stumbled upon strange behaviour of euca-authorize
command. I'm using Diablo release
If I create two security groups and add a rule using  euca-authorize
command to authorize ICMP traffic from one group to another, why am I
not able to add another rule for, say, tcp traffic?
Here are the commands I've tried:

[apetrovich at ostcore-wslab2 ]$ euca-describe-groups
GROUP    project1    default    default
[apetrovich at ostcore-wslab2 ]$ euca-add-group -d "mygroup description" mygroup
GROUP    mygroup    mygroup description
[apetrovich at ostcore-wslab2 ]$ euca-describe-groups
GROUP    project1    default    default
GROUP    project1    mygroup    mygroup description
[apetrovich at ostcore-wslab2 ]$ euca-add-group -d "another description" mygroup2
GROUP    mygroup2    another description
[apetrovich at ostcore-wslab2 ]$ euca-describe-groups
GROUP    project1    default    default
GROUP    project1    mygroup    mygroup description
GROUP    project1    mygroup2    another description
[apetrovich at ostcore-wslab2 ]$ euca-authorize --protocol icmp -t -1:-1
--source-group mygroup mygroup2
mygroup2 mygroup None icmp -1 -1 0.0.0.0/0
GROUP    mygroup2
PERMISSION    mygroup2    ALLOWS    icmp    -1    -1    GRPNAME
mygroup    FROM    CIDR    0.0.0.0/0
[apetrovich at ostcore-wslab2 ]$ euca-authorize --protocol tcp
--port-range 22 --source-group mygroup mygroup2
mygroup2 mygroup None tcp 22 22 0.0.0.0/0
ApiError: {'to_port': 22, 'group_id': 2L, 'protocol': 'tcp',
'from_port': 22, 'parent_group_id': 3L} - This rule already exists in
group

This seems very strange, so I digged in to the sources and found that
this is happens because of  the method _security_group_rule_exists of
the nova.api.ec2.CloudController:

def _security_group_rule_exists(self, security_group, values):
        """Indicates whether the specified rule values are already
           defined in the given security group.
        """
        for rule in security_group.rules:
            if 'group_id' in values:
                if rule['group_id'] == values['group_id']:
                    return rule['id']
            else:
                is_duplicate = True
                for key in ('cidr', 'from_port', 'to_port', 'protocol'):
                    if rule[key] != values[key]:
                        is_duplicate = False
                        break
                if is_duplicate:
                    return rule['id']
        return False

And it looks like it explicitly checks for the source group of the new
rule, and if there is already exists a rule with the same source group
it returns id of that group, so, it is not possible to add a different
rule with the same source group. Is it expected behaviour and I'm
missing something, or is it just a bug?