Repeated cron backup jobs

Hi, we've been using sameersbn/gitlab:8.12.5 docker image for a while and noticed this (run inside a container):

root@2ecfcd1201cb:/home/git/gitlab# head /var/spool/cron/crontabs/git        
# DO NOT EDIT THIS FILE - edit the master and reinstall.
# (/tmp/cron.git installed on Sat Mar 11 10:25:46 2017)
# (Cron version -- $Id: crontab.c,v 2.13 1994/01/17 03:20:37 vixie Exp $)
00 23 * * * /bin/bash -l -c 'cd /home/git/gitlab && bundle exec rake gitlab:backup:create SKIP= RAILS_ENV=production'
00 23 * * * /bin/bash -l -c 'cd /home/git/gitlab && bundle exec rake gitlab:backup:create SKIP= RAILS_ENV=production'
00 23 * * * /bin/bash -l -c 'cd /home/git/gitlab && bundle exec rake gitlab:backup:create SKIP= RAILS_ENV=production'
root@2ecfcd1201cb:/home/git/gitlab# cat /var/spool/cron/crontabs/git | wc -l
120

~120 lines of backup jobs. I believe it was configured on each container start?

Besides that, thank you for maintaining gitlab docker image :) .

Reproduce the issue in the sameersbn/gitlab:8.12.5 container and inspect /var/spool/cron/crontabs/git, then trace the container startup setup that installs the backup job. Done means repeated starts no longer add duplicate backup entries and the intended schedule remains present.