rollback on dummy database now has no effect (previously raised an er…

…ror). This means that custom 500 error pages (and e-mailed exceptions) now work even if a database has not been configured. Fixes #4429.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@5410 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/backends/dummy/base.py

@@ -12,6 +12,9 @@
 def complain(*args, **kwargs):
     raise ImproperlyConfigured, "You haven't set the DATABASE_ENGINE setting yet."
 
+def ignore(*args, **kwargs):
+    pass
+
 class DatabaseError(Exception):
     pass
 
@@ -21,7 +24,7 @@ class IntegrityError(DatabaseError):
 class DatabaseWrapper:
     cursor = complain
     _commit = complain
-    _rollback = complain
+    _rollback = ignore
 
     def __init__(self, **kwargs):
         pass