To reproduce:
1. Open users attached project "BugReport.zip"
2. Open "EmptyScene.unity" scene
3. Make sure that in the console Clear on Play is disabled
4. Open Test Runner
5. Select PlayMode tab and press Run All
6. Observe the console as IPostBuildCleanup is called (console warning -- in Cleanup)
7. Clear the console, select EditMode tab and press Run All
8. Observe the console as IPostBuildCleanup is not called

Expected result: IPostBuildCleanup is called in PlayMode and EditMode
Actual result: IPostBuildCleanup isn't called in EditMode

Reproduced on:
2018.2.0a1 2018.2.2f1

Not reproduced on:
2018.1.9f1 2018.3.0a6