OpenSUSE and SLES package installation shows "Signed with unknown key" warning

During installation of GitLab in OpenSUSE or SLES OS, the repo configuration step as well as installation step raises a warning regarding repo signature

bash-4.2# curl -sS https://packages.gitlab.com/install/repositories/gitlab/gitlab-ce/script.rpm.sh | sudo bash
Detected operating system as opensuse/42.1.
Checking for curl...
Detected curl...
Downloading repository file: https://packages.gitlab.com/install/repositories/gitlab/gitlab-ce/config_file.repo?os=opensuse&dist=42.1&source=script
done.
Retrieving repository 'gitlab_gitlab-ce' metadata ----------------------------------------------------------------------------------------------------------------------------[\]
File 'repomd.xml' from repository 'gitlab_gitlab-ce' is signed with an unknown key '14219A96E15E78F4'. Continue? [yes/no] (no): yes
Retrieving repository 'gitlab_gitlab-ce' metadata .........................................................................................................................[done]
Building repository 'gitlab_gitlab-ce' cache ..............................................................................................................................[done]
Specified repositories have been refreshed.

The repository is setup! You can now install packages.

bash-4.2# zypper install gitlab-ce
Retrieving repository 'gitlab_gitlab-ce-source' metadata ---------------------------------------------------------------------------------------------------------------------[|]
File 'repomd.xml' from repository 'gitlab_gitlab-ce-source' is signed with an unknown key '14219A96E15E78F4'. Continue? [yes/no] (no): yes

The line zypper --gpg-auto-import-keys refresh gitlab_gitlab-ce is already present in the packagecloud script, but my assumption is this

1. Before bash script is run, the keys are not yet added and hence the first warning
2. When bash script, the keys of gitlab_gitlab-ce repo is added, not gitlab_gitlab-ce-source, hence the second warning.

This is more of a guess and not at all tested.

/cc @gitlab-build-team

As this script is generated by PackageCloud, and not editable, perhaps we should open an issue with them?

cc @marin

This should be reviewed, post #2537 (closed)