[1.2.X] Fixed #15336 -- Silenced a warning about the DATABASES transi…

…tion when a database backend isn't specified. Thanks to Ivan Sagalaev for the report and patch.

Backport of r15571 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@15575 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/__init__.py

@@ -12,11 +12,12 @@
 # For backwards compatibility - Port any old database settings over to
 # the new values.
 if not settings.DATABASES:
-    import warnings
-    warnings.warn(
-        "settings.DATABASE_* is deprecated; use settings.DATABASES instead.",
-        PendingDeprecationWarning
-    )
+    if settings.DATABASE_ENGINE:
+        import warnings
+        warnings.warn(
+            "settings.DATABASE_* is deprecated; use settings.DATABASES instead.",
+            PendingDeprecationWarning
+        )
 
     settings.DATABASES[DEFAULT_DB_ALIAS] = {
         'ENGINE': settings.DATABASE_ENGINE,