It's a pretty easy to explain this bug. If you sheer a white sheep, you're supposed to get white wool. If you sheer a black sheep, you should get black wool, and so on and so forth. I've tested it on every single possible color of sheep and here were the results when sheered:
White sheep: black wool
Black sheep: white wool
Yellow sheep: blue wool
Pink sheep: cyan wool
Lime green sheep: purple wool
Gray sheep: light gray wool
Light blue sheep: brown wool
Magenta sheep: green wool
Purple sheep: lime green wool
Orange sheep: red wool
Blue sheep: yellow wool
Cyan sheep: pink wool
Light gray sheep: gray wool
Red sheep: orange wool
Green sheep: magenta wool
Duplicate of MC-53375 - If you have not, please use the search function in the future, to see if your bug has already been submitted. If you could not find the original report, please comment with the keywords you searched for.