Ticket #9640: fix_dont_attempt_to_preload_when_association_returns_nil.diff

activerecord/lib/active_record/association_preload.rb

@@ -21 +21 @@
-            preload_associations(records, parent, preload_options)
-            reflection = reflections[parent]
-            parents = records.map {|record| record.send(reflection.name)}.flatten
-
+ || parents.first.nil?
-              parents.first.class.preload_associations(parents, child)
-            end
-          end