Problem was introduced with r54648, which determined the initial interval for the Newton-Raphson method using the "total_time" of the collision - but this info is only defined for regular collisions, not for the raycasting used in boids to find the "ground object". To ensure correct behavior, now clear the collision info before using it (good practice in any case), then check the inv_total_time variable and use the standard 0.001 step if not defined.