How to reproduce:
1. Open the attached project
2. Enter Play mode

Actual result: In the console AudioSource.IsPlaying() booleans are logged, the first one is false.
Expected result: AudioSource should play in every frame.

Reproducible with: 2017.1.0f3, 2017.1.0p3, 2017.3.0a4.
Regression introduced in: 2017.1.0f3.
Not Reproducible with: 2017.1.0f2, 2017.1.0a1, 5.6.3f1, 5.5.4p2.

Note: This bug is not reproducible with 2017.2.0a1 - 2017.3.0a3, there is another regression in 2017.3.0a4.

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fixed in 2018.2.0a1.