To reproduce:
1. Open project attached by the user
2. Open "Main" scene if not opened
3. Hit play and in console notice that first xml file was loaded successfully, then UI element was added to the ExhibitManager game object (as a child)
4. Notice that second xml file is not loaded

Expected: After adding UI element, second xml file is loaded (script "ExhibitManager.cs").
Actual: Loading coroutine breaks after UI element is added.

Regression introduced in: 5.6.0b8
Reproduced with : 5.6.0f1, 5.6.1f1, 2017.1.0b6, 2017.2.0a1
Not reproduced with : 5.5.0f3, 5.6.0b7

Note: UI element is being added via script. Adding it as a parent does not break anything.

Fixed in: 2017.2.0a2
Backported to: 5.6.2p2, 2017.1.0f1