Support for these was removed in #3336 due to an "exec format error". This occurs when building non-amd64 images on an amd64 machine without a virtual machine emulating the instruction set. These builds worked fine when there were no execs in the Dockerfile. With the addition of adduser, this became broken.

Some ideas:

• Remove the exec in favor of copying a file
• Use QEMU for non-amd64 architectures