* Delete existing all-group vars on inventory sync (with overwrite-vars=True) instead of merging them.
* Implementation of inv var handling with file as db.
* Improve serialization to file of inv vars for src update
* Include inventory-level variable editing into inventory source update handling
* Add group vars to inventory source update handling
* Add support for overwrite_vars to new inventory source handling
* Persist inventory var history in the database instead of a file.
* Remove logging which was needed during development.
* Remove further debugging code and improve comments
* Move special handling for user edits of variables into serializers
* Relate the inventory variable history model to its inventory
* Allow for inventory variables to have the value 'None'
* Fix KeyError in new inventory variable handling
* Add unique-together constraint for new model InventoryGroupVariablesWithHistory
* Use only one special invsrc_id for initial update and manual updates
* Fix internal server error when creating a new inventory
* Print the empty string for a variable with value 'None'
* Fix comment which incorrectly states old behaviour
* Fix inventory_group_variables_update tests which did not take the new handling of None into account
* Allow any type for Ansible-core variable values
* Refactor misleading method names
* Fix internal server error when savig vars from group form
* Remove superfluous json conversion in front of JSONField
* Call variable update from create/update instead from validate
* Use group_id instead of group_name in model InventoryGroupVariablesWithHistory
* Disable new variable update handling for all regular (non-'all') groups
* Add live test to verify AAP-17690 (inv var deleted from source)
* Add functional tests to verify inventory variables update logic
* Fix migration which was corrupted by a rebase
* Add a more complex live test and resolve linter complaints
* Force overwrite_vars=False for updates from source on all-group
* Change behavior with respect to overwrite_vars
* Move call to django_validate_password to the correct method were the user object is available.
* Added tests for the Django password validation functionality.
Dirk Jülich