We want to call master_restart callback on start too - this callback
is used for cleaning up prometheus files. It has been added to
Omnibus already:
https://gitlab.com/gitlab-org/omnibus-gitlab/merge_requests/3350
So make sure that Unicorn example configs are up-to-date and that
the same callback is called for Puma too.
This allows us (and others) to test drive Puma without it affecting all
users. Puma can be enabled by setting the environment variable
"EXPERIMENTAL_PUMA" to a non empty value.
GitLab Bot