Repro steps:
- Open Scene1 from the attached project
- Select both particle systems, expand their shape module to see the shape gizmo, make sure Visualize Pivot in the renderer is turned on.
- Scale both systems up
- Observe how the billboard particles preserve their respective pivot offset, while the mesh one do not (gif attached)

Note:
- not a regression, issue persists in 2017.31p1
- seems like it could be linked to https://fogbugz.unity3d.com/f/cases/976091/, though it looked correct there.