as this has been proved by Gorodkov in 2016 to be indeed the projective plane over H

https://arxiv.org/abs/1603.05541

CC: @jhpalmieri

Component: algebraic topology

Author: Frédéric Chapoton

Branch/Commit: ae5676b

Reviewer: John Palmieri

Issue created by migration from https://trac.sagemath.org/ticket/34568