Removed threading fallback imports.

Django imports threading in many other places without fallback.

tests/select_for_update/tests.py

@@ -1,7 +1,7 @@
 from __future__ import unicode_literals
 
+import threading
 import time
-import unittest
 
 from django.conf import settings
 from django.db import transaction, connection, router
@@ -15,14 +15,6 @@ from multiple_database.routers import TestRouter
 
 from .models import Person
 
-# Some tests require threading, which might not be available. So create a
-# skip-test decorator for those test functions.
-try:
-    import threading
-except ImportError:
-    threading = None
-requires_threading = unittest.skipUnless(threading, 'requires threading')
-
 
 # We need to set settings.DEBUG to True so we can capture the output SQL
 # to examine.
@@ -92,7 +84,6 @@ class SelectForUpdateTests(TransactionTestCase):
             list(Person.objects.all().select_for_update(nowait=True))
         self.assertTrue(self.has_for_update_sql(connection, nowait=True))
 
-    @requires_threading
     @skipUnlessDBFeature('has_select_for_update_nowait')
     def test_nowait_raises_error_on_block(self):
         """
@@ -173,7 +164,6 @@ class SelectForUpdateTests(TransactionTestCase):
             # database connection. Close it without waiting for the GC.
             connection.close()
 
-    @requires_threading
     @skipUnlessDBFeature('has_select_for_update')
     @skipUnlessDBFeature('supports_transactions')
     def test_block(self):
@@ -223,7 +213,6 @@ class SelectForUpdateTests(TransactionTestCase):
         p = Person.objects.get(pk=self.person.pk)
         self.assertEqual('Fred', p.name)
 
-    @requires_threading
     @skipUnlessDBFeature('has_select_for_update')
     def test_raw_lock_not_available(self):
         """