with the change 86f88ee7b074fc8193a445e0c8ece58c3058b6c3 we now lookup for the ncurses headers and lib but as they are not marked as mandatory the configure step will continue but build will fails as the registry tool can't be compiled.
Just stumbled over this when moderating the samba-cvs list...
Sorry for the delay!
I think this does not apply to 4.0 but only to 4.1 and master.
In master and 4.1 this has meanwhile been fixed with these commits:
So for my understanding this is fixed.
Matthieu: Please reopen if you still see issues.