HSV lock translucent pixel darkening

[NinthDesertDude]

When drawing with HSV locks, translucent pixels can have a darkening effect on the image, but only the first time you roll the brush over an area with the same HSV settings (even between brush strokes). Might be a premultiplication-related problem. Since it only happens once, it's manageable, but it's not ideal because it imparts artifacts.