1 files changed, 17 insertions, 1 deletions
diff --git a/django/contrib/admin/__init__.py b/django/contrib/admin/__init__.py
index 8396ffc6b3..bb856a1241 100644
--- a/django/contrib/admin/__init__.py
+++ b/django/contrib/admin/__init__.py
@@ -2,12 +2,26 @@ from django.contrib.admin.options import ModelAdmin, HORIZONTAL, VERTICAL
 from django.contrib.admin.options import StackedInline, TabularInline
 from django.contrib.admin.sites import AdminSite, site
 
+# A flag to tell us if autodiscover is running.  autodiscover will set this to
+# True while running, and False when it finishes.
+LOADING = False
+
 def autodiscover():
     """
-    Auto-discover INSTALLED_APPS admin.py modules and fail silently when 
+    Auto-discover INSTALLED_APPS admin.py modules and fail silently when
     not present. This forces an import on them to register any admin bits they
     may want.
     """
+    # Bail out if autodiscover didn't finish loading from a previous call so
+    # that we avoid running autodiscover again when the URLConf is loaded by
+    # the exception handler to resolve the handler500 view.  This prevents an
+    # admin.py module with errors from re-registering models and raising a
+    # spurious AlreadyRegistered exception (see #8245).
+    global LOADING
+    if LOADING:
+        return
+    LOADING = True
+
     import imp
     from django.conf import settings
 
@@ -38,3 +52,5 @@ def autodiscover():
         # Step 3: import the app's admin file. If this has errors we want them
         # to bubble up.
         __import__("%s.admin" % app)
+    # autodiscover was successful, reset loading flag.
+    LOADING = False