Fixed #29917 -- Stopped collecting ModelAdmin.actions from base ModelAdmins.

docs/ref/contrib/admin/actions.txt

@@ -343,10 +343,8 @@ Conditionally enabling or disabling actions
     This returns a dictionary of actions allowed. The keys are action names, and
     the values are ``(function, name, short_description)`` tuples.
 
-    Most of the time you'll use this method to conditionally remove actions from
-    the list gathered by the superclass. For example, if I only wanted users
-    whose names begin with 'J' to be able to delete objects in bulk, I could do
-    the following::
+    For example, if you only want users whose names begin with 'J' to be able
+    to delete objects in bulk::
 
         class MyModelAdmin(admin.ModelAdmin):
             ...

docs/releases/2.2.txt

@@ -293,6 +293,27 @@ Database backend API
 * Third party database backends must implement support for partial indexes or
   set ``DatabaseFeatures.supports_partial_indexes`` to ``False``.
 
+Admin actions are no longer collected from base ``ModelAdmin`` classes
+----------------------------------------------------------------------
+
+For example, in older versions of Django::
+
+    from django.contrib import admin
+
+    class BaseAdmin(admin.ModelAdmin):
+        actions = ['a']
+
+    class SubAdmin(BaseAdmin):
+        actions = ['b']
+
+``SubAdmin`` will have actions ``'a'`` and ``'b'``.
+
+Now ``actions`` follows standard Python inheritance. To get the same result as
+before::
+
+    class SubAdmin(BaseAdmin):
+        actions = BaseAdmin.actions + ['b']
+
 :mod:`django.contrib.gis`
 -------------------------