ListImagesTest.test_index_no_params is checking by the list length, not the images identity

I'm running tests in parallel. I met an ERROR that appears it happened because some parallel test added some image. Tests should be comparing not by collection sizes, but by ids to avoid such race conditions.

16:09:12 #4 Simple test to see all fixture images returned ... FAIL
16:09:16
16:09:16 ======================================================================
16:09:16 FAIL: Simple test to see all fixture images returned
16:09:16 ----------------------------------------------------------------------
16:09:16 Traceback (most recent call last):
16:09:16 File "tempest/tests/image/test_images.py", line 202, in ListImagesTest.test_index_no_params
16:09:16 self = <tempest.tests.image.test_images.ListImagesTest testMethod=test_index_no_params>
16:09:16 198 """
16:09:16 199 Simple test to see all fixture images returned
16:09:16 200 """
16:09:16 201 images = list(self.client.images.list())
16:09:16 --> 202 self.assertEqual(10, len(images) - len(self.original_images))
16:09:16 images = [
...
16:09:16 <Image {u'status': u'active', u'name': u'f16-x86_64-openstack-sda', u'deleted': False, u'container_format': u'ovf', u'created_at': u'2012-12-10T14:57:12', u'disk_format': u'qcow2', u'updated_at': u'2012-12-10T14:57:18', u'id': u'22429bff-1c95-4a3b-affe-27eccdf7b284', u'owner': u'af07e16d3b9f48318b4a948b6ab6153c', u'protected': False, u'min_ram': 0, u'checksum': u'755122332caeb9f661d5c978adb8b45f', u'min_disk': 0, u'is_public': True, u'deleted_at': None, u'properties': {}, u'size': 213581824}>,
16:09:16 ]
16:09:16 AssertionError: 10 != 11
16:09:16 '10 != 11' = '%s != %s' % (safe_repr(10), safe_repr(11))
16:09:16 '10 != 11' = self._formatMessage('10 != 11', '10 != 11')
16:09:16 >> raise self.failureException('10 != 11')