Code review comment for lp:~cjwatson/launchpad/storm-0.21.0.99+lp413

Self-approving: this is a simple dependency upgrade to a reviewed change to Storm (effective change to Launchpad's branch: https://bazaar.launchpad.net/~launchpad-committers/storm/lp/revision/413), and I want to get it into production ASAP because the symptoms when branch scans time out at the moment are pretty strange.