Unable to delete branches on 'Branches' page after first changing the filter (BB-15972)

How to reproduce:

1. Open the "Branches" page.
2. Try to delete an active branch. (Successfully opens.)
3. Cancel.
4. Change to the "Merged" filter.
5. Try to delete a merged branch. (Fails to open.)
6. Cancel.
7. Reload the page.
8. Try to delete a merged branch. (Successfully opens.)
9. Cancel.
10. Change to the "Active" filter.
11. Try to delete an active branch. (Fails to open.)