Try to create more slim Docker layers

5 jobs for slim_docker in 18 minutes and 3 seconds (queued for 3 seconds)
Status Name Job ID Coverage
  Build Docker
passed build_docker_from_cache #547098

00:06:31

 
  Test
passed test_python2_mpi #547101

00:11:31

passed test_python2_scalar #547099

00:02:29

65.0%
passed test_python3_mpi #547102

00:11:07

passed test_python3_scalar #547100

00:01:40