Remove faulty save() method for user-group-mapping. Closes #60.

biscuit/core/models.py

@@ -105,13 +105,6 @@ class Person(SchoolRelated):
                                                      defaults={'name': value})
         self.primary_group = group
 
-    def save(self, *args, **kwargs):
-        if self.primary_group:
-            if self.primary_group not in self.member_of.all():
-                self.member_of.add(self.primary_group)
-
-        return super().save(*args, **kwargs)
-
     def __str__(self) -> str:
         return '%s, %s' % (self.last_name, self.first_name)