[1.6.x] Fixed #21202 -- Maintained atomicity when the server disconnects.

Thanks intgr for the report.

This commit doesn't include a test because I don't know how to emulate a
database disconnection in a cross-database compatible way.

Also simplified a 'backends' test that was constrained by this problem.

Backport of 81761508 from master

1 files changed, 0 insertions, 7 deletions

diff --git a/tests/backends/tests.py b/tests/backends/tests.py
index 0da5cb85e2..e62f564851 100644
--- a/tests/backends/tests.py
+++ b/tests/backends/tests.py
@@ -611,13 +611,6 @@ class BackendTestCase(TestCase):
         with self.assertRaises(DatabaseError):
             cursor.execute(query)
 
-
-class IsUsableTests(TransactionTestCase):
-    # Avoid using a regular TestCase because Django really dislikes closing
-    # the database connection inside a transaction at this point (#21202).
-
-    available_apps = []
-
     # Unfortunately with sqlite3 the in-memory test database cannot be closed.
     @skipUnlessDBFeature('test_db_allows_multiple_connections')
     def test_is_usable_after_database_disconnects(self):