Repro steps:
1. Open Scene1 from the attached project
2. Select the Particle system in the scene and make sure that in the Shape module "Single Material" is set to 1.
3. Try changing that value to 0 and observe that the particle still spawn from the same location
4. With the value still at 0, change the mesh to another mesh (or none) and back to Sphere001.
5. Observe that the particles now spawn from the new location.

Notes:
- Not a regression, happens in 2017.1.0p5, in 2017.2, and still present in 2017.3