From b13d260b11fc8415510e3d40ebb5d084a6f28518 Mon Sep 17 00:00:00 2001
From: Zachary Scott <e@zzak.io>
Date: Sat, 24 May 2014 13:22:52 -0700
Subject: [PATCH] Skip if the association was already loaded.

---
 activerecord/lib/active_record/associations/preloader.rb | 1 +
 1 file changed, 1 insertion(+)

diff --git a/activerecord/lib/active_record/associations/preloader.rb b/activerecord/lib/active_record/associations/preloader.rb
index 42571d6af09c5..7519fec10ab2b 100644
--- a/activerecord/lib/active_record/associations/preloader.rb
+++ b/activerecord/lib/active_record/associations/preloader.rb
@@ -143,6 +143,7 @@ def preloaders_for_one(association, records, scope)
       def grouped_records(association, records)
         h = {}
         records.each do |record|
+          next unless record
           assoc = record.association(association)
           klasses = h[assoc.reflection] ||= {}
           (klasses[assoc.klass] ||= []) << record