container:push error when Docker containerd enabled

[jgillard]

We bumped into this when someone new joined the team, and this setting inside Docker was enabled for new installations but not for everyone else:

When doing heroku container:push -a APP web we see this error, and the only way around it we've discovered is turning off this rather obscure setting in Docker. It took quite a while to track this cause down.

[eablack]

Thanks, I've been able to reproduce this. We'll look into changes to handle this scenario. We should at least provide explicit documentation that we don't support containerd.