This change is similar to https://github.com/ansible/ansible/pull/10465
It extends the logic there to also support none types. Right now if you have
a '!!null' in yaml, and that var gets passed around, it will get converted to
a string.
eg. defaults/main.yml
```
ENABLE_AWESOME_FEATURE: !!null # Yaml Null
OTHER_CONFIG:
secret1: "so_secret"
secret2: "even_more_secret"
CONFIG:
hostname: "some_hostname"
features:
awesame_feature: "{{ ENABLE_AWESOME_FEATURE}}"
secrets: "{{ OTHER_CONFIG }}"
```
If you output `CONFIG` to json or yaml, the feature flag would get represented in the output
as a string instead of as a null, but secrets would get represented as a dictionary. This is
a mis-match in behaviour where some "types" are retained and others are not. This change
should fix the issue.
I also updated the template test to test for this and made the changes to v2.
Added a changelog entry specifically for the change from empty string to null as the default.
Made the null representation configurable.
It still defaults to the python NoneType but can be overriden to be an emptystring by updating
the DEFAULT_NULL_REPRESENTATION config.
892e230514