Removed erroneous reference to to_s_fast in tests

Author: peterc

test/test_bitarray.rb

@@ -38,7 +38,7 @@ def test_random_side_effects
       ba2[index] = 0
       index
     end
-    assert_equal(@public_ba.to_s, @public_ba.to_s_fast)
+    #assert_equal(@public_ba.to_s, @public_ba.to_s_fast)
 
     @public_ba.size.times do |i|
       assert_equal(@public_ba[i], on.include?(i) ? 1 : 0)