Fixed init method of legacy BaseSetting class

The "return" statement was only a minor improvement, the breaking code was the passed "self" argument.

- fixes #8996
- fixes #9006

CHANGELOG.txt

@@ -166,6 +166,7 @@ Changelog
  * Fix: Ensure that `BaseSiteSetting` / `BaseGenericSetting` objects can be pickled (Andy Babic)
  * Fix: Ensure `DocumentChooserBlock` can be deconstructed for migrations (Matt Westcott)
  * Fix: Resolve frontent console error and unintented console logging issues (Matt Wescott, Paarth Agarwal)
+ * Fix: Resolve issue with sites that have not yet migrated away from `BaseSetting` when upgrading to Wagtail 4.0 (Stefan Hammer)
 
 
 3.0.1 (16.06.2022)

docs/releases/4.0.md

@@ -223,6 +223,7 @@ The bulk of these enhancements have been from Paarth Agarwal, who has been doing
  * Ensure that `BaseSiteSetting` / `BaseGenericSetting` objects can be pickled (Andy Babic)
  * Ensure `DocumentChooserBlock` can be deconstructed for migrations (Matt Westcott)
  * Resolve frontent console error and unintented console logging issues (Matt Wescott, Paarth Agarwal)
+ * Resolve issue with sites that have not yet migrated away from `BaseSetting` when upgrading to Wagtail 4.0 (Stefan Hammer)
 
 
 ## Upgrade considerations

wagtail/contrib/settings/models.py

@@ -217,4 +217,4 @@ class BaseSetting(BaseSiteSetting):
             category=RemovedInWagtail50Warning,
             stacklevel=2,
         )
-        return super().__init__(self, *args, **kwargs)
+        super().__init__(*args, **kwargs)