Can't return list of docker repository images through API
You are using an out of date api: https://docs.docker.com/v1.8/reference/api/docker-io_api/#list-library-repository-images
I tried to look for the last one without success.
Anyway, this behavior is correct, because in codacy-pylint you dont have multiple Dockefiles, you only have one Dockerfile and you apply tags on them.
For the ubuntu image, There are multiple Dockerfiles involved, that's why this URL returns a lot of stuff.
I assume what you really want is: https://index.docker.io/v1/repositories/codacy/codacy-pylint/tags
Probably you have to introduce your proyect to the official library. Here you have more information about how to do this: