Wrong solution to problem 9

[rokn]

At the solutions page for problem 9 from the 99 problems : https://wiki.haskell.org/99_questions/Solutions/9

The, currently, second solution is not correct and shouldn't be listed.
The solutions text states:

Another simple recursive solution
grp [] = []
grp (x:xs) = (x:(filter (==x) xs)):(grp $ filter (/=x) xs)

[mignon-p]

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