Several modules use "== None" instead of "is None"

$ grep -R '== None' *
bin/nova-manage: if host == None:
bin/nova-manage: if host == None:
bin/nova-manage: if host == None:
bin/nova-manage: if name == None:
nova/auth/manager.py: if user == None:
nova/auth/manager.py: if project == None:
nova/auth/manager.py: if access == None:
nova/auth/manager.py: if secret == None:
nova/api/ec2/cloud.py: if criteria == None:
nova/api/ec2/cloud.py: if lst == None or lst == []:
nova/virt/libvirt_conn.py: if devdst == None:
nova/virt/libvirt_conn.py: if devdst == None:
nova/compute/monitor.py: if cputime_last_updated == None:
nova/compute/api.py: instance.display_name == None):
nova/compute/instance_types.py: if name == None:
nova/compute/instance_types.py: if name == None:
nova/log.py: if context == None:
nova/image/local.py: if image == None:
nova/image/s3.py: if service == None:
nova/network/xenapi_net.py: if network_ref == None:
nova/tests/api/openstack/test_servers.py: if public_addresses == None:
nova/tests/test_scheduler.py: self.assertTrue(ret == None)
nova/tests/test_scheduler.py: self.assertTrue(ret == None)
nova/db/sqlalchemy/migrate_repo/versions/010_add_os_type_to_instances.py: .where(instances.c.os_type == None)\
nova/db/sqlalchemy/api.py: models.FixedIp.network_id == None)