MRs no longer require successful pipelines, and Webhooks stopped triggering

We have 4 Webhooks that each used to trigger builds on our remote CI server (Jenkins) on MR events and Push events. That was working fine. Also, we have our Gitlab database configured to require a successful pipeline before allowing a merge. This was working fine (could not Accept, i.e. Merge, an MR until the pipeline completed successfully) with versions 10.4.0-ee and prior for many months.

Just the other day, we updated to Gitlab 10.5.6-ee. Now merge requests are not triggering builds on Jenkins, and MR’s do not require a successful build to be merged. Our settings still appear to be the same:


When I Test one of those Webhooks for Push, Note, or Merge Request events, I get a 500 (“Whoops, something went wrong on our end,” etc.).

Is this a known problem? Was there a change in the semantics of “Only allow merge requests to be merged if the pipeline succeeds”?