Valentin David authored Aug 14, 2018 and Valentin David committed Aug 16, 2018

Ostree mirrors were not sharing the same local repository, so it was
impossible the request refs from the right local repository when data
was fetched from a mirror rather than upstream.

Instead of having several repository with one remote each, we now
have one repository with several remotes.

This fixes #538.

Fix ostree repository mirroring

See merge request !667

os.errno does no longer work with Python 3.7

Closes #577.