repocheck.log : where is it?

I got an email saying that one project failed its last repository check.

Last repository check (2 days ago) failed. See repocheck.log for error messages.

The repository is a very large repository with over 880k commits, 35k tags, and 20G on disk storage. I assume the git gc or whatever ran timed out.

However the repocheck.log under /admin/logs is empty. I've been searching in all PODs but can't find the log file either. Where is it?

From : https://docs.gitlab.com/ee/administration/logs.html#repocheck-log

repocheck.log 
This file lives in /var/log/gitlab/gitlab-rails/repocheck.log for Omnibus GitLab packages or in /home/git/gitlab/log/repocheck.log for installations from source.
It logs information whenever a repository check is run on a project.