The changes in 4.3 to fail (return -1) if there are no coverage files to append broke all of our builds. We needed that to success for our Travis + Coveralls set up. Now we are forced to peg at 4.2. Fails here: https://travis-ci.org/Miserlou/Zappa/builds
Please add a '--no-strict' or similar so we don't need to do this.