Container might have stopped between checking `is_running` and
calling `stop()`, which then threw an exception.
Signed-off-by: Ben Firshman <ben@firshman.co.uk>
For parity with the Docker CLI, allow environment variables without
values to be automatically resolved to their values on the host.
Signed-off-by: Ryan Brainard <brainard@heroku.com>
Conflicts:
tests/integration/service_test.py