One off containers no longer link to themselves

[bfirsh]

Regression since 0.3.2.

[bfirsh]

Here's the test which obviously isn't working properly: https://github.com/orchardup/fig/blob/0f5a56b3c20b477eeda99a24add2a4c54a1655f7/tests/service_test.py#L184-L188