[QA] Transitive impersonation fails

[jnweiger]

Seen while testing impersonate-0.5.2-rc.2 on core 10.11.0-rc.2

• enable impersonte app
• Admin adds user alice to group alice-g and makes user alice group admin of alice-g
• Admin adds user bob to group alice-g
• Admin enters settings -> user authentication and switches to
  (*) Allow group admins of specific groups to impersonate the users within those groups
  with a group list of [alice-g]
• Admin impersonates alice
• Now as alice, we try to imersonate bob. This fails. BAD

---

• When logged in as a fresh browser session as alice,
• Alice impersonates bob, and this succeeds.

Expected behaviour:

• As user alice one should be able to test the permissions setup, even if this is about testing further impersonations.
  I'd consider this a use case for impersonate. Or is that intentionally blocked?

[phil-davis]

PR #63 prevents this since 2017. Sadly that PR has words like "please don't merge this until I test the problem is fixed" but there is no link to an issue. So we do not know why this transitive impersonation was prevented.