Installing gitlab-ee breaks existing Gitolite installation

Summary

I tried to install Gitlab (apt-get install gitlab-ee) on an Ubuntu 18.04 server with an existing 'git' user which was used for Gitolite. This changed the location of the home directory for the 'git' user, thus breaking the existing Gitolite installation. There was no warning at all. The installation procedure at https://docs.gitlab.com/omnibus/development/openshift/README.html does not contain any warnings.

Steps to reproduce

Try apt-get install gitlab-ee on an Ubuntu server with an existing user named 'git'.

Example Project

No project involved.

What is the current bug behavior?

The home directory of the 'git' user will change from whatever it was to /var/opt/gitlab without warning or confirmation.

What is the expected correct behavior?

This should at least trigger a warning during installation, asking the user to confirm that the existing git user can be modified. It would be better to use a username like 'gitlab' which is less likely to have an existing role unrelated to gitlab.

Relevant logs and/or screenshots

Output of checks

Results of GitLab environment info

Not available. I had to urgently uninstall gitlab because it breaks my existing server setup.

Results of GitLab application Check

Not available. I had to urgently uninstall gitlab because it breaks my existing server setup.

Possible fixes

~bug