Reproduction steps:
1. Open the attached project "testing972662.zip";
2. Open the demo scene;
3. Enter a play mode;
4. Observe the results in the Console.

Expected results: when the particle system stops playing, there should be the result in the console, that the coroutine has finished.
Actual results: particle system playing is in the loop and coroutine cannot be finished.

Reproduced on: 2017.1.0p4, 2017.1.2p3, 2017.2.0p3, 2017.3.0b11, 2018.1.0a6.
Not reproduced on: 2017.1.0p3 and lower.
Regression has started in 2017.1.0p4.