Bug#1002376: python-aiosqlite: FTBFS: AttributeError: module 'mistune' has no attribute 'BlockGrammar'

[Benjamin Hof]

Control: affects 1001591 + src:python-aiosqlite

This looks like the mistune v2 incompatibility with m2r.

Upstream switched from m2r to sphinx-mdinclude (a m2r fork compatible
to mistune v2) in git.