Assigning nil to an attachment still deals with validations correctly

lib/paperclip.rb

@@ -255,7 +255,7 @@ module Paperclip
         valid_types = [options[:content_type]].flatten
         
         unless attachment.original_filename.blank?
-          unless options[:content_type].blank?
+          unless valid_types.blank?
             content_type = attachment.instance_read(:content_type)
             unless valid_types.any?{|t| t === content_type }
               options[:message] || "is not one of the allowed file types."

test/paperclip_test.rb

@@ -177,6 +177,21 @@ class PaperclipTest < Test::Unit::TestCase
           Dummy.send(:"validates_attachment_#{validation}", :avatar, options)
           @dummy = Dummy.new
         end
+        context "and assigning nil" do
+          setup do
+            @dummy.avatar = nil
+            @dummy.valid?
+          end
+          if validation == :presence
+            should "have an error on the attachment" do
+              assert @dummy.errors.on(:avatar)
+            end
+          else
+            should "not have an error on the attachment" do
+              assert_nil @dummy.errors.on(:avatar)
+            end
+          end
+        end
         context "and assigned a valid file" do
           setup do
             @dummy.avatar = valid_file