Caused by own rB6dc7266cf1f4. When overriding context for constraint operators (such as in constraint tests), it could happen that context "active_pose_bone" is set, but "pose_bone" isnt. Now check for both in ED_object_pose_constraint_list.
Caused by own rB6dc7266cf1f4. When overriding context for constraint operators (such as in constraint tests), it could happen that context "active_pose_bone" is set, but "pose_bone" isnt. Now check for both in ED_object_pose_constraint_list.