Moby: Allow `--entrypoint` to be set to `null` in a `docker run` or `docker create`

I would like to be able to "unset" an ENTRYPOINT at the command line when creating a container.

Using this Dockerfile and entrypoint.sh as an example:

Dockerfile:

FROM alpine
ADD entrypoint.sh /entrypoint.sh
RUN chmod 755 /entrypoint.sh
ENTRYPOINT ["/entrypoint.sh"]
CMD echo foobar

entrypoint:

#!/bin/sh
echo "I am an entrypoint"
exec "$@"

If I wanted to unset the entrypoint, I would like to be able to run this: docker run --entrypoint='' --rm -it image echo foo

I would expect this to produce the following output:

but it does the following instead:

I am an entrypoint
foo

Providing some way for docker run or docker create to force the ENTRYPOINT to be null without having to create another image would be great.