fix warnings imports in fixtures tests

tests/fixtures_model_package/tests.py

 from __future__ import unicode_literals
 
+import warnings
+
 from django.core import management
 from django.db import transaction
 from django.test import TestCase, TransactionTestCase
@@ -100,7 +102,6 @@ class FixtureTestCase(TestCase):
         )
 
         # Load a fixture that doesn't exist
-        import warnings
         with warnings.catch_warnings(record=True):
             management.call_command("loaddata", "unknown.json", verbosity=0, commit=False)
 

tests/fixtures_regress/tests.py

@@ -4,6 +4,7 @@ from __future__ import absolute_import, unicode_literals
 
 import os
 import re
+import warnings
 
 from django.core.serializers.base import DeserializationError
 from django.core import management
@@ -441,7 +442,6 @@ class TestFixtures(TestCase):
 
     def test_loaddata_not_existant_fixture_file(self):
         stdout_output = StringIO()
-        import warnings
         with warnings.catch_warnings(record=True):
             management.call_command(
                 'loaddata',