'package_prerequisite' Makefile target depends on 'golang-go' to be already installed

The Makefile 'package_prerequisite' target should install all package dependencies (on Ubuntu 18.04), including 'go'. But it actually depends on 'go' being already installed on the system. If it's not, the following error message will occur:

~/icn$ make package_prerequisite
pushd /home/gvancuts/icn/env/metal3 && ./01_install_package.sh && popd
~/icn/env/metal3 ~/icn
++ dirname /home/gvancuts/icn/env/metal3
+ LIBDIR=/home/gvancuts/icn/env
+ source /home/gvancuts/icn/env/lib/common.sh
++ set -eu -o pipefail
++ UBUNTU_BIONIC='Ubuntu 18.04.2 LTS'
++ DOWNLOAD_PATH=/opt/icn
++ LOCAL_APT_REPO=/opt/icn/apt
++ PIP_CACHE_DIR=/opt/icn/pip-cache-dir
++ BUILD_DIR=/opt/icn/build-dir
++ CONTAINER_IMAGES_DIR=/opt/icn/docker-dir
++ KUBE_VERSION=v1.15.0
++ POD_NETWORK_CIDR=10.244.0.0/16
++ PODMAN_CNI_CONFLIST=https://raw.githubusercontent.com/containers/libpod/v1.4.4/cni/87-podman-bridge.conflist
++ BS_DHCP_INTERFACE=
++ BS_DHCP_INTERFACE_IP=
++ BS_DHCP_DIR=/opt/icn/dhcp
++ IRONIC_IMAGE=integratedcloudnative/ironic:v1.0-icn
++ IRONIC_INSPECTOR_IMAGE=integratedcloudnative/ironic-inspector:v1.0-icn
++ IRONIC_BAREMETAL_IMAGE=integratedcloudnative/baremetal-operator:v2.0-icn
++ IPA_DOWNLOADER_IMAGE=integratedcloudnative/ironic-ipa-downloader:v1.0-icn
++ IRONIC_BAREMETAL_SOCAT_IMAGE=alpine/socat:latest
++ IRONIC_DATA_DIR=/opt/ironic
++ IRONIC_INTERFACE=
++ IRONIC_PROVISIONING_INTERFACE=provisioning
++ IRONIC_IPMI_INTERFACE=
++ IRONIC_PROVISIONING_INTERFACE_IP=172.22.0.1
++ IRONIC_IPMI_INTERFACE_IP=
++ BM_IMAGE_URL=https://cloud-images.ubuntu.com/bionic/current/bionic-server-cloudimg-amd64.img
++ BM_IMAGE=bionic-server-cloudimg-amd64.img
+++ go env GOPATH
/home/gvancuts/icn/env/lib/common.sh: line 43: go: command not found
++ M3PATH=/src/github.com/metal3-io
Makefile:27: recipe for target 'package_prerequisite' failed
make: *** [package_prerequisite] Error 127