Handle entrypoint when not in PATH, but in CWD

Created by: jopasserat

Typically happened to me with this image: https://hub.docker.com/r/biomedia/abdominal_stitching/

In this image, the Dockerfile would look like this:

WORKDIR /vol/medic02/users/xxx/coding/medical/mira/build/stitching

ENTRYPOINT ["./stitching"]

where stitching is a binary present in the CWD but CWD is not in PATH. Docker behaves this way and executes the entrypoint in the CWD.