MR widget "copy branch name" button tooltip occasionally shows `undefined`
Summary
The tooltip on the MR widget's "copy branch name" button occasionally displays "undefined":
Steps to reproduce
- Navigate to a merge request
- Hover over the "copy branch name" button until the tooltip is shown
- Click the button and leave the mouse over the button
- The tooltip should update to read "Copied"
- Move the mouse off the button and then hover over the button again
What is the current bug behavior?
The tooltip reads "undefined" for a split second before updating to read "Copy branch name".
What is the expected correct behavior?
The tooltip never shows "undefined".
Output of checks
This bug happens on GitLab.com.