Standalone merge_requests endpoint filter by updated_after scope=all times out with 500

Summary

Filtering merge_requests with scope=all and updated_after as the filter breaks.

Steps to reproduce

curl -i --header "PRIVATE-TOKEN: xxx" "https://gitlab.com/api/v4/merge_requests?scope=all&updated_after=2019-02-28T14:30:17.141Z8&per_page=10"   

Example Project