Log Message:
py-bitstring: updated to 3.1.9

version 3.1.9
---------------------------------------
(version 3.1.8 was pulled due to serious issues)
Another maintenance release.

* Fixed a couple of outdated results in the readme (Issue 214).
* Some more documentation tidying.
* Turned off some debug code by default.
* Fixed a couple of failing tests in different Python versions.
* Fix for consistent pos initialisation semantics for different types.
* Change to allow wheels to be uploaded to PyPI.
* More work for LSB0 mode, but still not finished or documented (sorry).