The containerd image store is not supported with userns-remap, so the
daemon disables the containerd-snapshotter feature and refuses to start
when it is explicitly enabled.
The containerd-migration feature was not covered by this, so a daemon
with both userns-remap and containerd-migration still switched to the
containerd image store.
Refuse to start in that case too, with the same kind of error as for
containerd-snapshotter.
Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
Paweł Gronowski
699057d8b8