batch changes: preview changesets selection has strange behaviour

Created by: bobheadxi

• Sourcegraph version: 155342_2022-06-17_8bb79a02abd7
• Platform information: Chrome

Steps to reproduce

1. Create a batch change and apply a spec
2. Wait for changesets to generate
3. In the preview page, click "view more" until all changesets visible
4. Check "select all", doesn't actually select all.
5. Select all all, does select all
6. Uncheck one, unchecks everything (except some?)

Video: https://www.loom.com/share/93a4961e57404f689d44b04b3e3d2914 , the preview is here: https://k8s.sgdev.org/users/robert/batch-changes/pr-auditor-patch-test/executions/QmF0Y2hTcGVjOiI2amRTbG5ZSm5yRiI=/preview

I was only able to reproduce this in the preview page, and not the changesets page