Steps:
1. Open attached project
2. Load Test scene
3. In the scene, observe that there are no Prefab overrides on the Prefab in the Overrides dropdown.
4. Select the child "Text".
5. Observe what the width value of the RectTransform is.
6. In the Text component, add some character to the text string.
7. Back to Root of prefab instance and open Overrides window
8. Select Text component and Revert it from Comparison window
==>
RectTransform appears in Overrides window and is shown as override
9. Click somewhere else to unfocus Overrides window
10. Open Overrides window
==> No RectTransform component is shown, but RevertAll and ApplyAll buttons are still visible

Expected: After step 8 the Overrides windows is empty

Take a look into attached movie for details