`Error fetching refs` is shown when trying to select source project for a merge request

Summary

Error fetching refs message is shown when trying to select source project for a merge request at project_name/merge_requests/new page.

Steps to reproduce

  • open some project, go to Merge Requests and click New Merge Requests
  • click source project name and start typing anything, you will get the error Error fetching refs Screen_Shot_2018-10-16_at_12.55.07_PM

Example Project

Can be checked on any sample project

What is the current bug behavior?

Error fetching refs is shown, not possible to change source project.

What is the expected correct behavior?

The error should be more descriptive, and it should be possible to select source project.

Relevant logs and/or screenshots

Have not found any errors in GitLab logs and in the browser console.

Output of checks

  • This bug happens on GitLab.com.
  • Also reproduced on self-managed GitLab 11.3.4.