You seem to be using Debian version stretch.This maps to Debian "jessie"...

[giuliomoro]

## Populating apt-get cache...

+ apt-get update
Ign:1 http://cdn-fastly.deb.debian.org/debian stretch InRelease
Hit:2 http://cdn-fastly.deb.debian.org/debian stretch Release
Reading package lists... Done

## Installing packages required for setup: lsb-release...

+ apt-get install -y lsb-release > /dev/null 2>&1

qemu: Unsupported syscall: 384
qemu: Unsupported syscall: 384

## You seem to be using Debian version stretch.
## This maps to Debian "jessie"... Adjusting for you...

## Confirming "jessie" is supported...

+ curl -sLf -o /dev/null 'https://deb.nodesource.com/node_7.x/dists/jessie/Release'
qemu: Unsupported syscall: 384