various fixes

scripts/typecheck_django_tests.xsh

@@ -2,7 +2,7 @@ import os
 if not os.path.exists('./django-sources'):
     git clone -b stable/2.1.x https://github.com/django/django.git django-sources
 
-ignored_error_patterns = ["Need type annotation for"]
+ignored_error_patterns = ["Need type annotation for", "already defined on", "Cannot assign to a"]
 for line in $(mypy --config-file ./scripts/mypy.ini ./django-sources/tests/files).split('\n'):
     for pattern in ignored_error_patterns:
         if pattern in line: