How to reproduce:
1. Download the tester-attached script(ReloadScene.cs)
2. Create a new Unity project and import the script
3. Make a copy of the SampleScene.scene to a folder outside of the Assets folder
4. Make some changes to the SampleScene.scene in the Editor and save it
5. Replace the SampleScene.scene outside of the Editor with the older copy of the scene
6. Return to the Editor and in the Reload prompt reload the scene

Expected result: EditorSceneManager.sceneOpened and EditorSceneManager.sceneOpening events are called
Actual result: EditorSceneManager.sceneOpened and EditorSceneManager.sceneOpening events are not called

Reproducible with: 2017.4.25f1, 2018.3.13f1, 2019.1.0f2, 2019.2.0a12