This is now fixed - the issue was basically that image manifests and config layers contain the image name, so if the name changes those layers will be replaced.

This is now fixed - the issue was basically that image manifests and config layers contain the image name, so if the name changes those layers will be replaced. The solution is to sort the packages in the name and return identical manifests. Docker doesn't seem to care about attaching names from registries that weren't in the config layer. There's a separate issue where Docker will re-download layers it already has because it doesn't just use the content hash for caching, but those layers will be identical. Working on figuring this one out ...