Many stubs in xml.etree.ElementTree use Union[str, bytes] as
return type. Mypy wants us to correctly handle each case. This
is correct, but not useful for us since we know that we'll always
get str. So force the return value to text_type, to supress mypy
errors.
This needs to be deployed to both staging and prod at the same
off-peak time (and the schema migration run).
At the time it is deployed, we need to make a few changes directly in
the database:
(1) UPDATE django_content_type set app_label='zerver' where app_label='zephyr';
(2) UPDATE south_migrationhistory set app_name='zerver' where app_name='zephyr';
(imported from commit eb3fd719571740189514ef0b884738cb30df1320)
