minor fixes to template function
- make sure it calls itself correctly, now passes same params as it recieves
- vars is reserved, changed for templatevars to avoid confustion
- forcing mustaches again since the removal broke 'listification' as per #9622
- fixes incorrectly successful tests using undefined var, now it is defined
- now returns empty list if items is None to avoid errors
fixes issues with listyfing failing too often
Expand playbook_dir in time for loading tasks

Fixes #9618
now only flattened ignores failonundefined cause of it's special need
Merge pull request #9629 from ansible/expand-variables

Expand playbook_dir in time for loading tasks
Update CHANGELOG.md
Merge pull request #9626 from bcoca/minor_template_fixes

fixes to template function
Bumping files for 1.9
Really update to a newer core module version :-)
Fix for a traceback in the git module
Is it not possible to set a comment in the same line
Don't template play vars by themselves, it's too early
Merge pull request #9639 from adrianlzt/bug/incorrect_comment

Is it not possible to set a comment in the same line
Refresh the core modules to pull in mysql fix
Merge pull request #9640 from hkariti/premature_template_playbook_vars

Don't template play vars by themselves, it's too early
Integration tests for #9242 and #9640
Pull in a fix for specifying a single role attribute for postgresql users
fine tuned lookup/templating errors
Merge pull request #9646 from bcoca/listify_template_fixes

fine tuned lookup/templating errors
codename fix :)