Branch name not shown before Merge request compare branch selection

Summary

Branch name not shown before Merge request compare branch selection

Steps to reproduce

Open any project Click on Merge Requests on the sidebar Click New merge request button Without selecting Source branch click Compare branches and continue button Again the same page will be reloaded but the dropdown box is empty and small

Example Project

https://gitlab.com/gitlab-org/gitlab-ce

What is the current bug behavior?

The dropdown box is empty and small

What is the expected correct behavior?

The dropdown box must again ask to select Source Branch

Relevant logs and/or screenshots

Before

before

After

Screenshot

Output of checks

This bug happens on GitLab.com, GitLab CE & EE