[1.0.X] `ModelAdmin` validation now runs when using the `site.register(Model, **kwargs)` form.

Backport if [10074] from trunk.


git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.0.X@10076 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/admin/sites.py

@@ -49,14 +49,15 @@ class AdminSite(object):
 
         If a model is already registered, this will raise AlreadyRegistered.
         """
+        if not admin_class:
+            admin_class = ModelAdmin
+
         # Don't import the humongous validation code unless required
         if admin_class and settings.DEBUG:
             from django.contrib.admin.validation import validate
         else:
             validate = lambda model, adminclass: None
 
-        if not admin_class:
-            admin_class = ModelAdmin
         if isinstance(model_or_iterable, ModelBase):
             model_or_iterable = [model_or_iterable]
         for model in model_or_iterable: