objects.all should return nil if bucket does not exist

lib/fog/aws/models/s3/objects.rb

@@ -13,10 +13,11 @@ module Fog
         model Fog::AWS::S3::Object
 
         def all(options = {})
-          bucket.collection.get(
+          collection = bucket.collection.get(
             bucket.name,
             options.reject {|key, value| !['delimiter', 'marker', 'max-keys', 'prefix'].include?(key)}
-          ).objects
+          )
+          collection && collection.objects
         end
 
         def bucket

spec/aws/models/s3/objects_spec.rb

@@ -33,6 +33,10 @@ describe 'Fog::AWS::S3::Objects' do
       @bucket.objects.all.should be_a(Fog::AWS::S3::Objects)
     end
 
+    it "should return nil if the bucket does not exist" do
+      bucket = s3.buckets.new(:name => 'notabucket')
+      bucket.objects.all.should be_nil
+    end
   end
 
   describe "#bucket" do