Changes of rigid body related settings during simulation will break the simulation (worked in 2.78c)
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System Information
Win7 x64

Blender Version
Broken: 2.79 RC (Master since between April and Juli)
Worked: 2.78c

Short description of error
Rigid body physics doesn't allow changes of related settings during simulation anymore. Either on mesh objects itself or on constraint objects a change immediately invalidates the simulation point cache and everything is lost.

Changing settings of physics during simulation is a crucial part for VFX work. This has been possible since Bullet is accessible from viewport, it was fully supported by Blender and Bullet in all past Blender releases. Also this breaks some Bullet related add-ons like the Bullet Constraints Builder on a fundamental level.

Exact steps for others to reproduce the error

  • Add rigid body property to the default cube
  • Start simulation and change mass of the object during simulation

Expected behavior: Cube continues to drop without noticeable influence
Current behavior: Cube suddenly jumps out of frame, orange cache indicator in timeline disappears