fix flake8 issues

Fixes the following flake8 issues:

- import shadowed by loop variable (flake8 F402)
- list comprehension redefines 'role_ref' (flake8 F812)

Change-Id: Ida64ccc9d7ee8b2ecd110a908615d3a94e93785c

keystone/assignment/backends/ldap.py

@@ -574,7 +574,7 @@ class RoleApi(common_ldap.BaseLdap):
         except ldap.NO_SUCH_OBJECT:
             roles = []
         res = []
-        for role_dn, _ in roles:
+        for role_dn, _role_attrs in roles:
             # ldap.dn.dn2str returns an array, where the first
             # element is the first segment.
             # For a role assignment, this contains the role ID,
@@ -608,7 +608,7 @@ class RoleApi(common_ldap.BaseLdap):
             conn.unbind_s()
 
         res = []
-        for role_dn, _ in roles:
+        for role_dn, _role_attrs in roles:
             # ldap.dn.str2dn returns a list, where the first
             # element is the first RDN.
             # For a role assignment, this contains the role ID,

keystone/assignment/backends/sql.py

@@ -15,7 +15,7 @@
 import six
 import sqlalchemy
 
-from keystone import assignment
+from keystone import assignment as keystone_assignment
 from keystone import clean
 from keystone.common import sql
 from keystone import config
@@ -33,7 +33,7 @@ class AssignmentType:
     GROUP_DOMAIN = 'GroupDomain'
 
 
-class Assignment(assignment.Driver):
+class Assignment(keystone_assignment.Driver):
 
     def _get_project(self, session, project_id):
         project_ref = session.query(Project).get(project_id)

keystone/tests/test_backend.py

@@ -640,7 +640,7 @@ class IdentityTests(object):
             tenant_id=project_ref['id'])
 
         self.assertEqual(set(role_list),
-                         set([role_ref['id'] for role_ref in role_ref_list]))
+                         set([r['id'] for r in role_ref_list]))
 
     def test_get_role_by_user_and_project(self):
         roles_ref = self.assignment_api.get_roles_for_user_and_project(

keystone/tests/test_content_types.py

@@ -19,7 +19,7 @@ from keystoneclient.common import cms
 import six
 from testtools import matchers
 
-from keystone.common import extension
+from keystone.common import extension as keystone_extension
 from keystone import config
 from keystone.tests import rest
 
@@ -110,13 +110,13 @@ class CoreApiTests(object):
 
     def test_public_extensions(self):
         r = self.public_request(path='/v2.0/extensions')
-        self.assertValidExtensionListResponse(r,
-                                              extension.PUBLIC_EXTENSIONS)
+        self.assertValidExtensionListResponse(
+            r, keystone_extension.PUBLIC_EXTENSIONS)
 
     def test_admin_extensions(self):
         r = self.admin_request(path='/v2.0/extensions')
-        self.assertValidExtensionListResponse(r,
-                                              extension.ADMIN_EXTENSIONS)
+        self.assertValidExtensionListResponse(
+            r, keystone_extension.ADMIN_EXTENSIONS)
 
     def test_admin_extensions_404(self):
         self.admin_request(path='/v2.0/extensions/invalid-extension',
@@ -128,8 +128,8 @@ class CoreApiTests(object):
 
     def test_admin_osksadm_extension(self):
         r = self.admin_request(path='/v2.0/extensions/OS-KSADM')
-        self.assertValidExtensionResponse(r,
-                                          extension.ADMIN_EXTENSIONS)
+        self.assertValidExtensionResponse(
+            r, keystone_extension.ADMIN_EXTENSIONS)
 
     def test_authenticate(self):
         r = self.public_request(

keystone/trust/backends/kvs.py

@@ -20,7 +20,7 @@ import copy
 from keystone.common import kvs
 from keystone import exception
 from keystone.openstack.common import timeutils
-from keystone import trust
+from keystone import trust as keystone_trust
 
 
 def _filter_trust(ref):
@@ -37,7 +37,7 @@ def _filter_trust(ref):
     return ref
 
 
-class Trust(kvs.Base, trust.Driver):
+class Trust(kvs.Base, keystone_trust.Driver):
     def create_trust(self, trust_id, trust, roles):
         trust_ref = copy.deepcopy(trust)
         trust_ref['id'] = trust_id