AttributeError when using non existent user

[Natalia Bidart]

Steps to reproduce:

(05:37:25 PM) achuni: 1- abris pycasa
(05:37:42 PM) achuni: 2- ponés algún username invalido, como 'bla'
(05:37:49 PM) achuni: 3- le das 'OK'
(05:38:20 PM) achuni: te dice "Invlid username '<email address hidden>', y te habilita el botón de '<email address hidden>' abajo a la izquierda
(05:38:30 PM) achuni: 4- click en el botón de '<email address hidden>'
(05:38:32 PM) achuni: >BANG!<

Traceback (most recent call last):
  File "/usr/bin/pycasa", line 465, in switch_to_albums
    self.update_status()
  File "/usr/bin/pycasa", line 303, in update_status
    found = self.is_album_view and self.pd.found or self.current_album.get_num_photos()
AttributeError: 'NoneType' object has no attribute 'get_num_photos'