Reproduction steps:
1. Open the attached project "SleepBug.zip";
2. Open the Main.unity scene;
3. Enter a play mode.

Expected results: The object should stay "asleep" even if it is in contact with another object.
Actual results: If the object is in the contact with the another collider on the moment when play mode starts, "start asleep" is not applied and object starts moving.

Reproduced on: 5.5.3p3, 5.6.3p1, 2017.1.0p5, 2017.2.0b8, 2017.3.0a5.