"Discard changes?" popup appears after clicking "Update" button

Created by: mike-r-mclaughlin

• Sourcegraph version: 3.42.0, 3.42.1
• Platform information: Chrome
• Reported by: https://github.com/sourcegraph/accounts/issues/3, https://github.com/sourcegraph/accounts/issues/6716

Steps to reproduce:

1. Go to Site Admin > Repositories > Manage code hosts
2. Click Edit next to an existing code host
3. Click "Update repositories" button
4. You will see a "Discard changes?" popup

Expected behavior:

Since the user clicked "Update repositories", no "Discard changes?" popup should appear.

Actual behavior:

/cc @jplahn @ryphil