Python 2.7 is reaching End Of Life and will no longer be supported by PSF from 1st January, 2020 (11 months from now).

https://www.python.org/dev/peps/pep-0373/
python/devguide#344

Should rasterio 1.0.x be the last version to support Python 2.x?

Related to Toblerity/Fiona#716