Can't trigger build with Jenkins Plugin on existing merge request

From ZenDesk: https://gitlab.zendesk.com/agent/tickets/26263

The only way merge requests trigger builds in Jenkins is when opening a completely new merge request, meaning:

If a merge request failed on Jenkins, you can’t reopen the same merge request, you can’t open a new merge request with the same commit, you must make a new commit and open a completely new merge request.

@ayufan, can you confirm if this is true?