Yes. If you enable it, the following tests fail: test_bignum_a_bignum_is_an_integer, test_format_a_host_name_with_a_component_too_long and test_format_a_regular_expression_with_unclosed_parens_is_invalid. The second two should be quite simple to fix (split on "." and check the length of each component, and try to compile the regex). I haven't looked at the first one. 

If failing tests are going to break your build, then I thought it was best to leave that commented out until all tests pass -- it's not like they used to pass and now they're broken; they never passed.