Pymssql authors have just pushed a release to PyPi that is _purposefully non-functional_ https://github.com/pymssql/pymssql/issues/668 <https://github.com/pymssql/pymssql/issues/668>
Unfortunately our version constraint on it from Airflow is a bit too broad, so this will be installed if you don't do anything else when you do `pip install 'apache-airfow[mssql]'. The work around if you need this dep is to do `pip install 'mssql~=2.1' 'apache-airfow[mssql]'` We'll fix this in a new release, but if anyone want's to look at replacing this with alternative that would be welcomed
