Merge request title with long number automatically links to commit


I’m hosting gitlab CE on my own server.
When the merge request title contains long number (e.g.104062231), it will automatically link to one of the commit of the master branch.

The reason why our merge requests contains such long number is that we ask our students to open a merge request, with their student ID as title, to their branch as a homework submission.

Is it a bug since the number is not the actual commit code? If not, is there any way to disable this function?

Thanks for your help!