[LNT] r207898 - Use Mann-Whitney U test to identify changes

[Anton Korobeynikov]

> In the docstring, it says "Use only when the n in each condition is < 20 and
> you have 2 independent samples of ranks."
And this is definitely wrong, since it does use the normal
approximation, which is valid for n > 20 in each sample ;)

-- 
With best regards, Anton Korobeynikov
Faculty of Mathematics and Mechanics, Saint Petersburg State University