github permissions regression test fails

Created by: uwedeportivo

• Sourcegraph version: 3.17 single server docker image
• Platform information: Docker for Mac

Steps to reproduce:

1. Run the instance and set up environment for regression test
2. Run this test:

yarn run test:regression:external-services -f 'External services permissions: GitHub'

https://github.com/sourcegraph/sourcegraph/blob/master/web/src/regression/external-services.test.ts#L263

(if you don't want to set up the regression test environment as described here: https://github.com/sourcegraph/sourcegraph/blob/master/web/src/regression/README.md#L1, you can do the test by hand. it's not that many steps)

Expected behavior:

test should pass

Actual behavior:

test fails, but if you turn off background permission sync, it passes

 "permissions.backgroundSync": {
    "enabled": false
  }