I have tried to update AP sources, and found that revision 1232 introduces strange throttle behavior:
when I switch to satbilze or fbw_a mode, motor spins with full speed (disregard throttle stick position).
It works fine in manual mode though (i.e. I can control motor speed with throttle stick).
Rollback to revision 1231 makes this problem gone.
I do not use airspeed sensor (#define AIRSPEED_SENSOR 0), shield version is 1, throttle pin is 13.
Is this a manifestation of some problem in my setup or it is a bug in the revision 1232?