Merge pull request #32431 from thaJeztah/17.04.x-cherry-pick-32425

[17.04.x] cherry-pick 32425 - fix install.sh of get.docker.com for debian-sudo

hack/install.sh

@@ -478,7 +478,7 @@ do_install() {
 
 			(
 			set -x
-			echo "$docker_key" | apt-key add -
+			echo "$docker_key" | $sh_c 'apt-key add -'
 			$sh_c "mkdir -p /etc/apt/sources.list.d"
 			$sh_c "echo deb \[arch=$(dpkg --print-architecture)\] ${apt_url}/repo ${lsb_dist}-${dist_version} ${repo} > /etc/apt/sources.list.d/docker.list"
 			$sh_c 'sleep 3; apt-get update; apt-get install -y -q docker-engine'