Members given access date/time is wrong (request date is shown)

Summary

I requested access to a Group on Friday and got the acces on Monday. In 'Group->Members' it's shown as "Given access 2 days ago" instead of "Given access 5 minutes ago".

The request timestamp is used instead of the granted timestamp.

Steps to reproduce

Request access for a group and wait some time before granting.

Using GitLab Enterprise Edition 11.3.4-ee 14d3a1dc