When I re-arranged the test-in-docker I didn't realize how .travis.yml
was extracting the results. This should fix it.
When running with test-in-docker we mount the source read-only on
/linux-ro/ inside the container and copy it over to /lorax/ for running
the tests.
The local directory ./.test-results/ is mounted on /test-results/ in the
container and the .coverage file is copied into there so that it is
available on the host.
(cherry picked from commit b61a91954a)
