Reproduction steps (thanks aruzicka):

 
on sat:

satellite-installer --foreman-proxy-plugin-remote-execution-script-remote-working-dir=/var/tmp/rex

on client

mkdir /var/tmp/rex
mount -t tmpfs -o size=8M tmpfs /var/tmp/rex

job

DIR="$(dirname "$0")"

echo "Consuming all space"
cat /dev/zero > "$DIR/zeroes"