I've attached a Blend file. I guess this bug is for Aligorith!
In the file, you have two similar bone setups, the first bone chain uses custom handles, and the second one uses traditional parenting to curve the bbone.
The green bones have a copy location constraint with the use_bbone_shape option.
Notice that when you rotate "bbone_handle1" and then reset the rotation, the green bone will not be refreshed and it will stay in the wrong position. If you do the same but with "bbone_handle2", everything works correctly. This last bone chain uses normal parenting, while the non working one uses custom handles.
Apart from this, I also noticed a visible lag when having this same scenario, but with the rig linked. Maybe it's all part of the same problem.