Cleaned up a test slightly.

We should catch all exceptions in the thread to ensure it doesn't die
with an unhandled exception. The type of the exception is already
checked further in the test.

tests/regressiontests/backends/tests.py

@@ -584,7 +584,7 @@ class ThreadTests(TestCase):
                 connections['default'] = main_thread_connection
                 try:
                     models.Person.objects.get(first_name="John", last_name="Doe")
-                except DatabaseError as e:
+                except Exception as e:
                     exceptions.append(e)
             t = threading.Thread(target=runner, args=[connections['default']])
             t.start()
@@ -594,21 +594,21 @@ class ThreadTests(TestCase):
         exceptions = []
         do_thread()
         # Forbidden!
-        self.assertTrue(isinstance(exceptions[0], DatabaseError))
+        self.assertIsInstance(exceptions[0], DatabaseError)
 
         # If explicitly setting allow_thread_sharing to False
         connections['default'].allow_thread_sharing = False
         exceptions = []
         do_thread()
         # Forbidden!
-        self.assertTrue(isinstance(exceptions[0], DatabaseError))
+        self.assertIsInstance(exceptions[0], DatabaseError)
 
         # If explicitly setting allow_thread_sharing to True
         connections['default'].allow_thread_sharing = True
         exceptions = []
         do_thread()
         # All good
-        self.assertEqual(len(exceptions), 0)
+        self.assertEqual(exceptions, [])
 
     def test_closing_non_shared_connections(self):
         """