Drone will now check that
from __future__ absolute_import, unicode_literals
is part of every Python source file, to ensure a consistent experience
across all versions of Python.
See #2392 for an instance where missing `unicode_literals` was causing
problems.
Add missing absolute_import, unicode_literals to all files
Explicitly ensure strings are of the correct types
Now that unicode_literals is in every file, some things that used to
be py2 `str`s were now `unicode` instead. This caused issues with
generated class / function names, which must be `str` in all versions of
Python. This means bytes in py2, and unicode in py3. A test also checked
for the incorrect type of SafeString. HTML content should always be
unicode, so this has been fixed.
