LDAP group sync: undefined method < for nil
Summary
Seen in https://gitlab.zendesk.com/agent/tickets/56350 - if an LDAP group sync times out, but the sync has never successfully completed, we compare nil < 1.hour.ago
Steps to reproduce
Kill the sync job partway through then leave GitLab turned off for > 1 hour
Expected behavior
Sync should be successfully cancelled in this instance
Actual behavior
NoMethodError is raised
/cc @dblessing