Cloud-init does not install puppet but runs the final module and succeeds according cloud-init?

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Summarize:

CentOS8 image with cloud-init-18.5-12 the following part failed “modules-final/config-scripts-user”.
This problem also occurs using the default cloud-init template in Foreman.

I have no clue yet why runcmd is exiting with exit 1.

Running runcmd manually or executing cloudinit.util.runparts("/var/lib/cloud/instance/scripts/") with python gives no hint at all what is going on, under the hood.

Any idea`s are welcome.

The template shown below, without invoking snippets is running fine.

<%#
kind: cloud-init
name: CloudInit default
model: ProvisioningTemplate
oses:
- CentOS
- Fedora
- Debian
- Ubuntu
-%>
<%#
This template accepts the following parameters:
- force-puppet: boolean (default=false)
- enable-puppetlabs-repo: boolean (default=false)
- enable-puppetlabs-puppet5-repo: boolean (default=false)
- enable-puppetlabs-puppet6-repo: boolean (default=false)
-%>
<%
  pm_set = @host.puppetmaster.empty? ? false : true
  puppet_enabled = pm_set || host_param_true?('force-puppet')
-%>

#cloud-config
hostname: <%= @host.name %>
fqdn: <%= @host %>
manage_etc_hosts: true
users: {}
runcmd:

- [ touch, /tmp/test ]
- [ setenforce, 0 ]
- [ rpm, -Uvh ,"https://yum.puppet.com/puppet6/puppet6-release-el-8.noarch.rpm" ]

phone_home:
  url: <%= foreman_url('built') %>
  post: []
  tries: 10