Code review comment for lp://staging/~sjakthol/update-manager/fix-slow-calculation

One more thing. If you run nosetests3 in your checkout, you'll see that the pep8 and pyflakes tests fail. Please fix those errors. But beyond that, I think this is good to approve.

(Don't worry if test_is_port_listening fails for you; that just means you aren't running ssh. It's not a good test.)