Description:
Unpacking nested Prefabs with references to each other causes references to be set back to Prefabs in Assets folder instead of GameObjects in Scene after Scene is reopened

How to reproduce:
1. Open the attached project "1252422.zip"
2. Open the "Test" Scene
3. Right-click "Parrent" GameObject in the Hierarchy window and click "Unpack"
4. Select "Child" GameObject in the Hierarchy window and notice the value of "Game Object Ref" field in "Component Referencer" Component
5. Save, close and reopen "Test" Scene (by opening Scene "a" and then reopening "Test" scene), and repeat step 4

Expected result: "Game Object Ref" field keeps a reference to GameObject in the Scene
Actual result: "Game Object Ref" field gets a reference to a "Parent" Prefab

Reproducible with: 2018.4.23f1, 2019.3.15f1, 2020.1.0b11, 2020.2.0a13