python3: fix inner iterator classes of csv_import

src/authentic2/csv_import.py

@@ -28,6 +28,7 @@ from django.core.validators import RegexValidator
 from django.db import IntegrityError
 from django.db.transaction import atomic
 from django.utils import six
+from django.utils.encoding import force_bytes
 from django.utils.encoding import force_text
 from django.utils.translation import ugettext as _
 
@@ -49,21 +50,32 @@ class UTF8Recoder(object):
     def __iter__(self):
         return self
 
-    def next(self):
-        return self.fd.next().encode('utf-8')
+    def __next__(self):
+        if six.PY2:
+            return self.fd.next().encode('utf-8')
+        else:
+            return force_text(self.fd.__next__().encode('utf-8'))
+
+    next = __next__
 
 
 class UnicodeReader(object):
     def __init__(self, fd, dialect='excel', **kwargs):
         self.reader = csv.reader(UTF8Recoder(fd), dialect=dialect, **kwargs)
 
-    def next(self):
-        row = self.reader.next()
-        return [s.decode('utf-8') for s in row]
+    def __next__(self):
+        if six.PY2:
+            row = self.reader.next()
+            return [s.decode('utf-8') for s in row]
+        else:
+            row = self.reader.__next__()
+            return [force_bytes(s).decode('utf-8') for s in row]
 
     def __iter__(self):
         return self
 
+    next = __next__
+
 
 class CsvImporter(object):
     rows = None