If the daemon is configured to use a mirror for the default (Docker Hub)
registry, the endpoint did not fall back to querying the upstream if the mirror
did not contain the given reference.
For pull-through registry-mirrors, this was not a problem, as in that case the
registry would forward the request, but for other mirrors, no fallback would
happen. This was inconsistent with how "pulling" images handled this situation;
when pulling images, both the mirror and upstream would be tried.
This patch brings the daemon-side lookup of image-manifests on-par with the
client-side lookup (the GET /distribution endpoint) as used in API 1.30 and
higher.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
07d2ad30e5