title: Mounting fails with docker compose but not with docker run
body: <p>I'm mounting a file with docker run:
  This works fine:</p>
  
  <pre><code>docker run  -v /path/to/myconfig.conf:/path/.to/myconfig.conf ..
  </code></pre>
  
  <p>But in docker-compose it's complaining:</p>
  
  <pre><code>volumes:
        - named-volume:/path
        - ./path-in-project/myconfig.conf:/path/.to/myconfig.conf
  </code></pre>
  
  <p>Error:</p>
  
  <pre><code>Cannot start service xxx: oci runtime error: container_linux.go:262: starting container process caused "process_linux.go:339: container init caused \"rootfs_linux.go:57: mounting \\\"/path/to/my/myconfig.conf\\\" to rootfs \\\"/var/lib/docker/aufs/mnt/249085892d6539519b0271c1490f23529c7bcaxxx5a471cc256ed83a6f4d\\\" at \\\"/var/lib/docker/aufs/mnt/249085892d6539519b0271c1490f23529c7bcaxxx5a471cc256ed83a6f4d/path/.to/myconfig.conf\\\" caused \\\"not a directory\\\"\""
  : Are you trying to mount a directory onto a file (or vice-versa)? Check if the specified host path exists and is the expected type
  </code></pre>