Reproduction Steps:
1. Import attached project.
2. Open "test" scene.
3. Select "Cube" in Hierarchy.
4. In Inspector, make the object static.
5. Select "Directional Light" in Hierarchy.
6. In Inspector, change the Baking property to any other.

Expected result: Unity commits changes.
Actual result: Unity doesn't stop compositing. (GIF attached)

Reproducible with: 5.5.2p1
Not reproducible with: 5.4.3p3, 5.5.0p3, 5.6.0b10
Regression introduced in: 5.5.0p4