make sure the I18nField defaultvalue is not passed by reference

src/c3nav/mapdata/fields.py

@@ -174,6 +174,9 @@ class I18nField(JSONField):
         kwargs.pop('null', None)
         super().__init__(verbose_name=verbose_name, default=(dict(default) if default else {}), null=False, **kwargs)
 
+    def get_default(self):
+        return self.default.copy()
+
     def deconstruct(self):
         name, path, args, kwargs = super().deconstruct()
         if self.default == {}:

src/c3nav/mapdata/models/base.py

@@ -52,11 +52,6 @@ class TitledMixin(SerializableMixin, models.Model):
     class Meta:
         abstract = True
 
-    def __init__(self, *args, **kwargs):
-        super().__init__(*args, **kwargs)
-        if 'titles' not in self.get_deferred_fields():
-            self.titles = self.titles.copy()
-
     def serialize(self, **kwargs):
         result = super().serialize(**kwargs)
         return result

src/c3nav/mapdata/models/locations.py

@@ -81,10 +81,6 @@ class Location(LocationSlug, AccessRestrictionMixin, TitledMixin, models.Model):
     class Meta:
         abstract = True
 
-    def __init__(self, *args, **kwargs):
-        super().__init__(*args, **kwargs)
-        self.titles = self.titles.copy()
-
     def serialize(self, detailed=True, describe_only=False, **kwargs):
         result = super().serialize(detailed=detailed, **kwargs)
         if not detailed: