cubicweb-oauth #4085738 get_next_login produces non-unicode strings [validation pending]

This leads, when a de-duplicating a new login, to an error :

ValidationError: 623483 (login-subject): incorrect value ('xxxxxxxx') for type "String"; you might want to try unicode

prioritynormal
typebug
done in0.3.1
load1.000
load left0.000
closed by#2c5a651f26c9 Make sure get_next_login returns a unicode string.
patchMake sure get_next_login returns a unicode string. [applied]