[db, casiasurf] added attack-type=None for real examples

bob/pad/face/database/casiasurf.py

@@ -41,10 +41,12 @@ class CasiaSurfPadFile(VideoPadFile):
       self.stream_type = stream_type
       if not isinstance(s.attack_type, str):
         attack_type = str(s.attack_type)
-        attack_type = None
       else:
         attack_type = s.attack_type
 
+      if attack_type == '0':
+        s.attack_type = None
+
       super(CasiaSurfPadFile, self).__init__(
             client_id=s.id,
             file_id=s.id,