[1.5.x] Fixed #19367 -- Fixed saving ContentFile in filesystem storage

This was not working properly when ContentFile was initialized with
an unicode string.
Thanks Alexey Boriskin for the report and the test.

Backport of 34dcf51e06 from master.

django/core/files/base.py

@@ -6,7 +6,7 @@ from io import BytesIO, StringIO, UnsupportedOperation
 from django.utils.encoding import smart_text
 from django.core.files.utils import FileProxyMixin
 from django.utils import six
-from django.utils.encoding import python_2_unicode_compatible
+from django.utils.encoding import force_bytes, python_2_unicode_compatible
 
 @python_2_unicode_compatible
 class File(FileProxyMixin):
@@ -134,8 +134,11 @@ class ContentFile(File):
     A File-like object that takes just raw content, rather than an actual file.
     """
     def __init__(self, content, name=None):
-        content = content or b''
-        stream_class = StringIO if isinstance(content, six.text_type) else BytesIO
+        if six.PY3:
+            stream_class = StringIO if isinstance(content, six.text_type) else BytesIO
+        else:
+            stream_class = BytesIO
+            content = force_bytes(content)
         super(ContentFile, self).__init__(stream_class(content), name=name)
         self.size = len(content)
 

tests/regressiontests/file_storage/tests.py

@@ -560,6 +560,13 @@ class InconsistentGetImageDimensionsBug(unittest.TestCase):
 
 class ContentFileTestCase(unittest.TestCase):
 
+    def setUp(self):
+        self.storage_dir = tempfile.mkdtemp()
+        self.storage = FileSystemStorage(self.storage_dir)
+
+    def tearDown(self):
+        shutil.rmtree(self.storage_dir)
+
     def test_content_file_default_name(self):
         self.assertEqual(ContentFile(b"content").name, None)
 
@@ -576,7 +583,18 @@ class ContentFileTestCase(unittest.TestCase):
         retrieved content is of the same type.
         """
         self.assertTrue(isinstance(ContentFile(b"content").read(), bytes))
-        self.assertTrue(isinstance(ContentFile("español").read(), six.text_type))
+        if six.PY3:
+            self.assertTrue(isinstance(ContentFile("español").read(), six.text_type))
+        else:
+            self.assertTrue(isinstance(ContentFile("español").read(), bytes))
+
+    def test_content_saving(self):
+        """
+        Test that ContentFile can be saved correctly with the filesystem storage,
+        both if it was initialized with string or unicode content"""
+        self.storage.save('bytes.txt', ContentFile(b"content"))
+        self.storage.save('unicode.txt', ContentFile("español"))
+
 
 class NoNameFileTestCase(unittest.TestCase):
     """