AppScale/appscale-tools — pull request #147 by shatterednirvana (2013-02-11 19:24:53+00:00)
Title: Failing if secret key file is found instead of locations.yaml

Since it is written much earlier in the deployment process, the secret key file is a better file to check existence on than locations.yaml. If we use locations.yaml, we have a race condition that exists where a user can run two AppScale deployments with the same keyname, where the later one immediately fails, but writes its own secret key (later messing up the first deployment).