Invalid Kafo-generated hiera.conf

[mattock]

Recently the installer has started failing with these errors:

[ERROR 2019-03-20T05:45:35 main] Errors encountered during run:
[ERROR 2019-03-20T05:45:35 main]  Evaluation Error: Error while evaluating a Function Call, Lookup of key 'lookup_options' failed:  The Lookup Configuration a
t '/tmp/kafo_hiera20190320-5670-iw2i8y/hiera.conf' has wrong type, unrecognized key 'backends'

The offending hiera.conf looks like this:

---
:backends:
- yaml
:hierarchy:
- "%{::osfamily}"
- common
:yaml:
  :datadir: "/usr/share/puppetmaster-installer/config/data"
version: 5
defaults:
  datadir: "/tmp/kafo_hiera20190320-6062-di2vrb/data"
  data_hash: yaml_data
hierarchy:
- name: Kafo Answers
  path: kafo_answers.yaml
  datadir: "/tmp/kafo_hiera20190320-6062-di2vrb/data"
  data_hash: yaml_data

[mattock]

This can be reproduced trivially using the above hiera.conf without Kafo:

$ puppet apply --hiera_config=/tmp/hiera.conf -e 'notify { lookup('foo'): }'
Error: Evaluation Error: Error while evaluating a Function Call, Lookup of key 'lookup_options' failed: 
The Lookup Configuration at '/tmp/hiera.conf' has wrong type, unrecognized key 'backends'
The Lookup Configuration at '/tmp/hiera.conf' has wrong type, unrecognized key 'yaml' 
(line: 1, column: 10) on node localhost.