Tornado 6.0 doesn't support Python 2.7
Tornado 6.0 doesn't support Python 2.7 but sphinx-autobuild==0.7.1 just has
tornado>=3.2 as a requirement.
Collecting tornado>=3.2 (from sphinx-autobuild==0.7.1->-r requirements/documentation.txt (line 3)) Downloading http://172.18.0.1:3141/root/pypi/+f/3f8/db1394416371f/tornado-6.0.tar.gz (481kB) tornado requires Python '>= 3.5' but the running Python is 2.7.13
Sphinx-Autobuild hasn't had any commits since 2017.
It might be sensible to add
requirements/documentation.txt, at least until Mayan drops support for Python 2.7?
The alternative is file a bug against
sphinx-autobuild and wait for a new release, but that might take some time.