fix #18

Author: 高岩A

consul/base.py

@@ -1067,20 +1067,21 @@ def list(
                     self, policy=None, token=None):
                 """
                 This endpoint lists all the ACL roles.
-                :param *policy*: (string: "") - Filters the 
-                role list to those roles that are linked with 
-                the specific policy ID.
-                :header X-Consul-Token:
-                :return:
+                    :param *policy*: (string: "") - Filters the
+                    role list to those roles that are linked with
+                    the specific policy ID.
+                    :header X-Consul-Token:
+                    :return:
                 """
-                path = '/v1/acl/roles?policy=%s' % policy
+
+                if policy:
+                    path = '/v1/acl/roles?policy=%s' % policy
+                else:
+                    path = '/v1/acl/roles'
                 headers = {}
                 token = token or self.agent.token
                 if token:
                     headers['X-Consul-Token'] = token
-                
-                if policy:
-                    headers['X-Consul-Token'] = policy
 
                 return self.agent.http.get(CB.json(),
                                            path=path,