Do not allow floodfill to extend into negative coordinates #4017
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Resolves #4016
At the moment,
ImageDraw.floodfill
doesn't stop filling new pixels just because their coordinates happen to be negative - when filling the next pixels around (0, 0), it also uses (-1, -1). So it continues, and wraps around to the other side of the image.To demonstrate, with this image -
filling a coordinate in the upper left of this image before this fix gives -
This PR fixes it -