Permission denied for conan install unknown package

Summary

Permission denied when trying to get a conan package that doesn't exist in package registry.

Steps to reproduce

Run gitlab CI on Example project

Example Project

https://gitlab.com/jeremy.coulon.jrmc/conan-hello

What is the current bug behavior?

Trying to get a non existing package (here: cmake_installer) fails with error 403.

cmake_installer/3.15.4@conan/stable: Not found in local cache, looking in remotes...
cmake_installer/3.15.4@conan/stable: Trying with 'upload_repo'...
ERROR: Failed requirement 'cmake_installer/3.15.4@conan/stable' from 'hello/0.1@jeremy.coulon.jrmc+conan-hello/stable'
conans.errors.ForbiddenException: {"message":"403 Forbidden"}
During handling of the above exception, another exception occurred:
conans.errors.ForbiddenException: Permission denied for user: 'ci_user'. [Remote: upload_repo]

What is the expected correct behavior?

Trying to get a non existing package should succeed and return no result. Then conan client can try another remote to look for the missing package (eg. conan-center).

cmake_installer/3.15.4@conan/stable: Not found in local cache, looking in remotes...
cmake_installer/3.15.4@conan/stable: Trying with 'upload_repo'...
cmake_installer/3.15.4@conan/stable: Trying with 'conan-center'...
cmake_installer/3.15.4@conan/stable: Downloaded recipe revision 0
Installing package

Output of checks

This bug happens on GitLab.com