API: "Get a single repository tag" fails when using fully qualified :id

Summary

The API endpoint https://gitlab.com/api/v4/projects/c.lopez1%2Fmy-public-project/repository/tags/mytag replies 404 Not found whereas https://gitlab.com/api/v4/projects/3474724/repository/tags/mytag just works.

Steps to reproduce

1. Create a repository tag
2. Note the project id under the project "Settings"
3. Use the "GET a single repository" endpoint using the qualified project name as described in Summary.

Example Project

https://gitlab.com/c.lopez1/my-public-project/

What is the current bug behavior?

The endpoint returns 404

What is the expected correct behavior?

The endpoint should give the same response as if one were using the project id number instead of the the qualified name

Relevant logs and/or screenshots

Output of checks

This bug happens on GitLab.com