Conjugation of verbs with the ß in pattern.text.de appears to be broken

[whiskahs]

Attempting to conjugate verbs which contain the "ß" character results in a misspelling. Conjugating the same verb with "ss" in place of "ß" results in the correct spelling.

For example, "heißen" renders to "heeißen".

from pattern.text.de import conjugate

conjugate('heißt')
Out[3]: 'heeißen'

conjugate('heißen')
Out[4]: 'heeißen'

conjugate('heissen')
Out[5]: 'heissen'

conjugate('beißen')
Out[6]: 'beeißen'

conjugate('beissen')
Out[7]: 'beissen'