[XeTeX] Hyphenation around „ß“

[Philip Taylor]

Georg Pfeiffer wrote:

> There should be no difference, because the used word in the test have 
> the same spelling and hyphenation in both variants. The patterns should 
> be the same. The problem sticks anywhere between xetex and the output 
> (LaTeX for XeTeX, xltxtra, babel, polygrossia).

Well, I am confused (not an unusual state of affairs, many will opine).
My 1999 edition of the Collins German Dictionary (reformed orthography)
gives only "wusste", and gives it as the preterite of "wissen".

Does "wußte" exist in the Reformed Orthography, and if so,
with what meaning ?

** Phil.

[1] Collins German Dictionary, ISBN-10 0-00-470585-8,
unabbridged, 4th edition, > 2000 pp.