Evolve Mercurial extension: obsolescence markers not exchanged with https

I'd love to be able to use the evolve extension. It seems that it should work: BCLOUD-6710 so I tried to enable its use in Bitbucket Labs ("Enables Mercurial evolution support").

However, the obsolescence markers are not sent in the remote repository in Bitbucket.

See https://bitbucket.org/paugier/repo_test_evolve_fork

I use the most recent versions of mercurial and hg-evolve, installed with pip2 install mercurial hg-evolve -U --user.

hg --version
Mercurial Distributed SCM (version 4.9)
...

python2 -c "import hgext3rd.evolve as e; print(e.__version__)"
8.4.0