from Mitchell Stokes (moguri)
--- from the patch
With f-curves there are 3 rotation modes, rotation_euler, rotation_axis_angle, and rotation_quaternion. The IPO converter
was still simply looking for "rotation" f-curves instead of specific ones. This patch fixes that and also
fixes bug #19873 ( http://projects.blender.org/tracker/index.php?func=detail&aid=19873&group_id=9&atid=306
).