Test occurring after every Rails command

I've got a bit of a strange problem. It's been happening for a while, but it wasn't causing any problems, so I put it to the back burner.

After every Rails command, I seem to get the output of a blank test immediately following.

For example:

tom@tom-desktop-linux:~/code/workspace/mainsite$ ./script/about About your application's environment Ruby version 1.8.4 (i486-linux) RubyGems version 0.9.2 Rails version 1.2.2 Active Record version 1.15.2 Action Pack version 1.13.2 Action Web Service version 1.2.2 Action Mailer version 1.3.2 Active Support version 1.4.1 Application root /home/tom/code/workspace/mainsite Environment development Database adapter mysql Database schema version 21 Loaded suite ./script/about Started

Finished in 0.000416 seconds.

0 tests, 0 assertions, 0 failures, 0 errors

And the same happens with ./script/runner and ./script/server (but only Webrick). It seems like it executes a blank rake test. I've not changed anything inside these files, so I can only imagine I've managed to wrap rake into something strange like boot.rb or environment.rb - but these look totally sensible and nothing obvious is in there!

Any suggestions to help me track this one down?