[soc2009/multidb] Fix a number of tests when run under an old style settings (i.e. using the DATABASE_* settings).

git-svn-id: http://code.djangoproject.com/svn/django/branches/soc2009/multidb@11779 bcc190cf-cafb-0310-a4f2-bffc1f526a37

TODO

@@ -11,6 +11,15 @@ Required for v1.2
     * validate() on a field
         * name/purpose clash with Honza?
         * any overlap with existing methods?
+ * Check test failures with old-style (non-multi-db) settings file
+    * custom_pk
+    * backends
+ * Check test failures with MySQL MyISAM
+    * serializers_regress
+    * fixtures
+    * lookup
+    * transactions
+    * model_regress
 
 Optional for v1.2
 ~~~~~~~~~~~~~~~~~

django/db/__init__.py

@@ -17,9 +17,19 @@ if not settings.DATABASES:
         "settings.DATABASE_* is deprecated; use settings.DATABASES instead.",
         PendingDeprecationWarning
     )
+    
+    if settings.DATABASE_ENGINE in ("postgresql", "postgresql_psycopg2",
+        "sqlite3", "mysql", "oracle"):
+        engine = "django.db.backends.%s" % settings.DATABASE_ENGINE
+        warnings.warn(
+            "Short names for DATABASE_ENGINE are deprecated; prepend with 'django.db.backends.'",
+            PendingDeprecationWarning
+        )
+    else:
+        engine = settings.DATABASE_ENGINE
 
     settings.DATABASES[DEFAULT_DB_ALIAS] = {
-        'ENGINE': settings.DATABASE_ENGINE,
+        'ENGINE': engine,
         'HOST': settings.DATABASE_HOST,
         'NAME': settings.DATABASE_NAME,
         'OPTIONS': settings.DATABASE_OPTIONS,

django/db/utils.py

@@ -6,13 +6,7 @@ from django.utils.importlib import import_module
 
 def load_backend(backend_name):
     try:
-        module = import_module('.base', 'django.db.backends.%s' % backend_name)
-        import warnings
-        warnings.warn(
-            "Short names for DATABASE_ENGINE are deprecated; prepend with 'django.db.backends.'",
-            PendingDeprecationWarning
-        )
-        return module
+        return import_module('.base', 'django.db.backends.%s' % backend_name)
     except ImportError, e:
         # Look for a fully qualified database backend name
         try: