Fails tests with ruby 1.9

With ruby 1.9.3p194 (2012-04-20 revision 35410) [x86_64-linux] I get the following test failures:

```
  1) Failure:
test_33(ArrayFieldsTest) [test/arrayfields.rb:165]:
<[nil]> expected but was
<[]>.

  2) Failure:
test_80(ArrayFieldsTest) [test/arrayfields.rb:306]:
<[nil]> expected but was
<[]>.

  3) Failure:
test_81(ArrayFieldsTest) [test/arrayfields.rb:317]:
<[nil]> expected but was
<[]>.
```
