Code review comment for lp:~canonical-platform-qa/ubuntu-system-tests/clean-install

I've just made an update which adds a try_import() helper to import the modules in question. Please take a look to see if you're happy with this approach: http://bazaar.launchpad.net/~canonical-platform-qa/ubuntu-system-tests/clean-install/revision/456

If so I'll update the rest of the branch to use this helper. Thanks.