Blender Version
Broken: Blender RC
Worked: (optional)

Short description of error
Changing the Shape option of the Physics settings of a Force Field object does not refresh the animation.

Exact steps for others to reproduce the error

1. Open file attached;
2. Run animation from frame 1 to 255;
3. See how each particle (inside the range) moves equally in a single direction and velocity.
4. Stop the animation and go back to frame 1;
5. Change the Shape option of the Force Field object from Plane to Point;
6. Play animation;
7. See the particles are still moving in a single direction and velocity;
8. Stop the animation and go back to frame 1;
9. Change any other parameters in the Force Field settings (for example disable Rotation);
10. Play animation;
11. Now the particles move with different velocities according to the shape.

This is not a regression, the same is seen in 2.79.