To reproduce:
1. Open the "scene" scene in the attached project
2. Select the "GameObject" from the Hierarchy
3. Enter the Play mode
4. In the Inspector, in the SkidSound component, using the Volume slider, slide from 0 to the right
5. Perform step 4 several times

Desired outcome: Sliding the volume slider from left to right gradually increases the volume.
Actual result: Each time you slide from 0 to anything more than 0, there is a volume bump.

Note: The volume bump also happens when AudioSource is muted.

Reproduced with 2017.1.0b7, 2017.1.0b10, 2017.2.0a2, 2017.2.0a4
Not reproduced with 5.5.4p1, 5.6.2f1, 2017.1.0b6, 2017.2.0a1
Regression introduced in 2017.1.0b7, 2017.2.0a2