This was revealed in one of the test cases.

Steps to reproduce:

1. Create a new user
2. Grant the user view space permissions to a particular space
3. Delete the user
4. Attempt to delete the space

When the space is deleted (e.g. in the tearDown methods), an exception is thrown, because the SpacePermission cannot be found. Charles discovered this was due to the permission not being removed from the space when it was removed from the database.