Description of problem:
We upload different images to each docker repositories but all the docker repositories ended up associating to the same manifest list and/or manifests. The associating manifest list/manifests are not belonged to any of the uploaded docker images.

How reproducible:
Easy

Steps to Reproduce:
1. Sync any repository from upstream docker registry so that the Satellite will have some existing docker manifests.
2. Follow KCS "https://access.redhat.com/solutions/4175551" to prepare multiple docker image tarball using skopeo.
3. Create a docker repository for each of the image and upload the tarball using the following commands
~~~
hammer repository create --product <product> --organization <organization> --name <repository name> --content-type docker
hammer repository upload-content --name <repository name> --organization <organization> --product <product> --path /<path>/<to>/<image tarball>/<image name>.tar
~~~

Actual results:
Upload commands completed successfully but if we use the following command to check the repository manifest, we will found that they are all associating to the same manifests.
~~~
hammer docker manifest list --repository <repository name> --organization <organization> --product <product>
~~~

Expected results:
Upload works correctly.

Additional info:

It appears that the upload-content is not implemented to support Pulp3 container plugin.