improvements ...

[vanhauser-thc]

Sadly I cannot check if this works as the basic building of magma currently does not seem to work:

Step 9/52 : RUN mkdir -p /home && 	groupadd -g ${GROUP_ID} magma && 	useradd -l -u ${USER_ID} -K UMASK=0000 -d /home -g magma magma && 	chown magma:magma /home
 ---> Running in ebe23d9a644e
groupadd: GID '0' already exists
The command '/bin/sh -c mkdir -p /home && 	groupadd -g ${GROUP_ID} magma && 	useradd -l -u ${USER_ID} -K UMASK=0000 -d /home -g magma magma && 	chown magma:magma /home' returned a non-zero code: 4

[hazimeh]

This may have occurred in case you ran the build script as root. Did you try running as a non-root user?