su username -c "some command" ends with an error message: /bin/sh Permission denied

I tried create Docker container based on image imported from minirootfs

https://fr.alpinelinux.org/alpine/v3.5/releases/x86_64/alpine-minirootfs-3.5.0-x86_64.tar.gz

or based on image from Docker hub library

Dockerfile

FROM alpine:3.5

When I start Docker container (and create user)

docker exec -it container_name /bin/sh

and run command inside like:

su username -c "some command"
su username -c "ls"

or

docker exec -it container_name su username -c "ls"

I get error message: /bin/sh Permission denied

/bin/sh is shell from /etc/passwd

I tried gradually create user with shell:

• /bin/ash
• /bin/false
• /sbin/nologin

with same result.

(from redmine: issue id 6621, created on 2017-01-04)