[BUG MechJeb 1.9.*] When decoupling a stage with a MechJeb, the center of mass is not reset and cause the ship to spn furiously.
This is the "inverted inputs" problem previously discussed here:
http://kerbalspaceprogram.com/forum/showthread.php/12384-PLUGIN-PART-0-16-Anatid-Robotics-MuMech-MechJeb-Autopilot-v1-9?p=238965&viewfull=1#post238965