Collection - Test if creating duplicate content results in 400
CLOSED - WONTFIX
- Evaluate if we already have similar tests in place.
- Create duplicate content
- Assert that an HTTP Bad Request - 400 was raised
- Assert that an error (e.g. "There is already a file content unit with relativepath 'foo.tar.gz' and artifact '/pulp/api/v3/artifacts/1/'.") is returned