[FIXED] Platformer may move into isolated pixels on last frames [BUG?]

[Nepster]

After placing the last brick, the terrain checks for the platformer are relaxed. Under some circumstances this can result in the platformer moving into isolated pixels:
Look at the attached image. On the left side is the original situation, the right despictes the shrugging animation of the same lemmings. In the case of the upper lemming, the two white pixels were seen and the lemming got stalled, moves only one pixel in the last frame and starts shrugging one pixel further to the left than usual. The lower lemming does not detect the isolated pixel, moves on his last frame directly onto the pixel and starts shrugging there.

I do not yet know of any way one can abuse this behavior, but given the general guideline "lemmings in terrain cause only trouble", I propose the following:
  Even in the lower situation, stall the lemming, i.e. move him only one pixel before starting shrugging.