OrderedHash#update should alias to merge bang

lib/mongo/util/ordered_hash.rb

@@ -88,6 +88,8 @@ class OrderedHash < Hash
       super(other)
     end
 
+    alias :update :merge!
+
     def inspect
       str = '{'
       str << (@ordered_keys || []).collect { |k| "\"#{k}\"=>#{self.[](k).inspect}" }.join(", ")

test/test_ordered_hash.rb

@@ -130,6 +130,14 @@ class OrderedHashTest < Test::Unit::TestCase
     assert_equal ['crab', 'apple', 3, 'foo'], @oh.values
   end
 
+  def test_update
+    other = OrderedHash.new
+    other['f'] = 'foo'
+    noob = @oh.update(other)
+    assert_equal @ordered_keys + ['f'], noob.keys
+    assert_equal [1, 2, 3, 'foo'], noob.values
+  end
+
   def test_inspect_retains_order
     assert_equal '{"c"=>1, "a"=>2, "z"=>3}', @oh.inspect
   end