[1.8.x] Fixed #24252 -- Forced lazy __str__ to utf-8 on Python 2

Thanks Stanislas Guerra for the report and Tomas Ehrlich for
the review.
Backport of cd0ceaa102 from master.

1 files changed, 4 insertions, 0 deletions

diff --git a/django/utils/functional.py b/django/utils/functional.py
index aa0d6f850a..37cc7c7f0f 100644
--- a/django/utils/functional.py
+++ b/django/utils/functional.py
@@ -120,6 +120,7 @@ def lazy(func, *resultclasses):
                     cls.__str__ = cls.__text_cast
                 else:
                     cls.__unicode__ = cls.__text_cast
+                    cls.__str__ = cls.__bytes_cast_encoded
             elif cls._delegate_bytes:
                 if six.PY3:
                     cls.__bytes__ = cls.__bytes_cast
@@ -142,6 +143,9 @@ def lazy(func, *resultclasses):
         def __bytes_cast(self):
             return bytes(func(*self.__args, **self.__kw))
 
+        def __bytes_cast_encoded(self):
+            return func(*self.__args, **self.__kw).encode('utf-8')
+
         def __cast(self):
             if self._delegate_bytes:
                 return self.__bytes_cast()