Rails 3.1.x - "kill -9" only way to stop tests

Ever since upgrading to Rails 3.1 on one of my projects tests can no
longer be stopped using Ctrl+C but must instead be stopped will "kill
-9" (regular kill will also not stop the tests).

This is on Ubuntu 11.04 with Ruby 1.9.2p0 and Rails 3.1.1.

What is the code in the test that causes this to happen?

Peter

All tests. Ctrl+C seems to interrupt the first test and does nothing
after that. The only gem I can speculate being a problem might be
shoulda.

How do you start your tests?

rake test

or

ruby -Itest test/unit/whatever

There was some speculation on this issue here:

https://github.com/seattlerb/minitest/issues/46