Following sequence doesn't work:
# docker login
# docker tag <image-hash> <docker-hub-id>/<name>
# docker push <docker-hub-id>/<name>
fails with
The push refers to a repository [registry.fedoraproject.org/<docker-hub-id>/<name>]
9c360ae72584: Preparing
55b267618723: Preparing
unauthorized: authentication required
It looks like docker tries to push the image to the wrong repository.
Fedora doesn't use Docker Hub as default repository by default. One has to explicitly state the target repo: