Fixed #19101 -- Decoding of non-ASCII POST data on Python 3.

Thanks Claude Paroz.

django/http/multipartparser.py

@@ -110,7 +110,7 @@ class MultiPartParser(object):
         # HTTP spec says that Content-Length >= 0 is valid
         # handling content-length == 0 before continuing
         if self._content_length == 0:
-            return QueryDict(MultiValueDict(), encoding=self._encoding), MultiValueDict()
+            return QueryDict('', encoding=self._encoding), MultiValueDict()
 
         # See if the handler will want to take care of the parsing.
         # This allows overriding everything if somebody wants it.

django/http/request.py

@@ -276,6 +276,9 @@ class QueryDict(MultiValueDict):
             encoding = settings.DEFAULT_CHARSET
         self.encoding = encoding
         if six.PY3:
+            if isinstance(query_string, bytes):
+                # query_string contains URL-encoded data, a subset of ASCII.
+                query_string = query_string.decode()
             for key, value in parse_qsl(query_string or '',
                                         keep_blank_values=True,
                                         encoding=encoding):

tests/regressiontests/requests/tests.py

@@ -12,7 +12,7 @@ from django.http import HttpRequest, HttpResponse, parse_cookie, build_request_r
 from django.test.client import FakePayload
 from django.test.utils import override_settings, str_prefix
 from django.utils import unittest
-from django.utils.http import cookie_date
+from django.utils.http import cookie_date, urlencode
 from django.utils.timezone import utc
 
 
@@ -353,6 +353,16 @@ class RequestsTests(unittest.TestCase):
         self.assertRaises(Exception, lambda: request.body)
         self.assertEqual(request.POST, {})
 
+    def test_non_ascii_POST(self):
+        payload = FakePayload(urlencode({'key': 'España'}))
+        request = WSGIRequest({
+            'REQUEST_METHOD': 'POST',
+            'CONTENT_LENGTH': len(payload),
+            'CONTENT_TYPE': 'application/x-www-form-urlencoded',
+            'wsgi.input': payload,
+        })
+        self.assertEqual(request.POST, {'key': ['España']})
+
     def test_alternate_charset_POST(self):
         """
         Test a POST with non-utf-8 payload encoding.