Merge branch 'master' into nested_has_many_through

Conflicts:
	activerecord/lib/active_record/associations/has_many_association.rb
	activerecord/lib/active_record/associations/through_association_scope.rb

1 files changed, 14 insertions, 11 deletions

diff --git a/activerecord/lib/active_record/relation/spawn_methods.rb b/activerecord/lib/active_record/relation/spawn_methods.rb
index 648a02f1cc..a61a3bd41c 100644
--- a/activerecord/lib/active_record/relation/spawn_methods.rb
+++ b/activerecord/lib/active_record/relation/spawn_methods.rb
@@ -28,17 +28,20 @@ module ActiveRecord
 
       merged_wheres = @where_values + r.where_values
 
-      # Remove duplicates, last one wins.
-      seen = {}
-      merged_wheres = merged_wheres.reverse.reject { |w|
-        nuke = false
-        if w.respond_to?(:operator) && w.operator == :==
-          name       = w.left.name
-          nuke       = seen[name]
-          seen[name] = true
-        end
-        nuke
-      }.reverse
+      unless @where_values.empty?
+        # Remove duplicates, last one wins.
+        seen = Hash.new { |h,table| h[table] = {} }
+        merged_wheres = merged_wheres.reverse.reject { |w|
+          nuke = false
+          if w.respond_to?(:operator) && w.operator == :==
+            name              = w.left.name
+            table             = w.left.relation.name
+            nuke              = seen[table][name]
+            seen[table][name] = true
+          end
+          nuke
+        }.reverse
+      end
 
       merged_relation.where_values = merged_wheres