Fix final Py3 test failure.

This is a combination of three fixes. The tests had to be adjusted, as
the cgi module in Python 3 won't work without a content-length header
anymore. This is a side-effect of python/cpython@5c23b8e.
Without the content length, the limit / read_bytes calculation is off,
and we end up with three fieldstorage instances each with an empty byte,
rather than one instance with a content of `test\n`.

The second part is a heavy handed workaround for closing the BytesIO
instance underlying the FieldStorage too early. In Python 2.7, there
wasn't a `__del__` defined yet. There's a good chance, a proper fix
could also be related to http://bugs.python.org/issue23700 and
http://bugs.python.org/issue18879, but I couldn't work out if
something similar was indeed the issue here.

Finally the TemporaryFileWrapper no longer needs special closing/del
logic under Python 3, as the implementation changed. There is no
`close_called` attribute anymore, but rather a more complex `_closer`
indirection.

src/ZPublisher/HTTPRequest.py

@@ -1644,18 +1644,19 @@ class TemporaryFileWrapper(_TemporaryFileWrapper):
     and doesn't complain about such a move either.
     """
 
-    unlink = staticmethod(unlink)
-    isfile = staticmethod(isfile)
+    if PY2:
+        unlink = staticmethod(unlink)
+        isfile = staticmethod(isfile)
 
-    def close(self):
-        if not self.close_called:
-            self.close_called = True
-            self.file.close()
+        def close(self):
+            if not self.close_called:
+                self.close_called = True
+                self.file.close()
 
-    def __del__(self):
-        self.close()
-        if self.isfile(self.name):
-            self.unlink(self.name)
+        def __del__(self):
+            self.close()
+            if self.isfile(self.name):
+                self.unlink(self.name)
 
 
 class ZopeFieldStorage(FieldStorage):
@@ -1664,6 +1665,13 @@ def make_file(self, binary=None):
         handle, name = mkstemp()
         return TemporaryFileWrapper(os.fdopen(handle, 'w+b'), name)
 
+    def __del__(self):
+        # Only call close on file object, cStringIO/BytesIO objects
+        # would be closed too early.
+        if (self.file is not None and
+                isinstance(self.file, TemporaryFileWrapper)):
+            self.file.close()
+
 
 # Original version: zope.publisher.browser.FileUpload
 class FileUpload(object):

src/ZPublisher/tests/testHTTPRequest.py

@@ -749,7 +749,9 @@ def test_close_removes_stdin_references(self):
         s = BytesIO(TEST_FILE_DATA)
         start_count = sys.getrefcount(s)
 
-        req = self._makeOne(stdin=s, environ=TEST_ENVIRON.copy())
+        environ = TEST_ENVIRON.copy()
+        environ['CONTENT_LENGTH'] = str(len(TEST_FILE_DATA))
+        req = self._makeOne(stdin=s, environ=environ)
         req.processInputs()
         self.assertNotEqual(start_count, sys.getrefcount(s))  # Precondition
         req.close()
@@ -759,7 +761,9 @@ def test_processInputs_w_large_input_gets_tempfile(self):
         # checks fileupload object supports the filename
         s = BytesIO(TEST_LARGEFILE_DATA)
 
-        req = self._makeOne(stdin=s, environ=TEST_ENVIRON.copy())
+        environ = TEST_ENVIRON.copy()
+        environ['CONTENT_LENGTH'] = str(len(TEST_LARGEFILE_DATA))
+        req = self._makeOne(stdin=s, environ=environ)
         req.processInputs()
         f = req.form.get('largefile')
         self.assertTrue(f.name)
@@ -769,12 +773,14 @@ def test_processInputs_with_file_upload_gets_iterator(self):
         # collector entry 1837
         s = BytesIO(TEST_FILE_DATA)
 
-        req = self._makeOne(stdin=s, environ=TEST_ENVIRON.copy())
+        environ = TEST_ENVIRON.copy()
+        environ['CONTENT_LENGTH'] = str(len(TEST_FILE_DATA))
+        req = self._makeOne(stdin=s, environ=environ)
         req.processInputs()
-        f = req.form.get('file')
-        self.assertEqual(list(f), ['test\n'])
+        f = req.form.get('smallfile')
+        self.assertEqual(list(f), [b'test\n'])
         f.seek(0)
-        self.assertEqual(next(f), 'test\n')
+        self.assertEqual(next(f), b'test\n')
 
     def test__authUserPW_simple(self):
         user_id = 'user'
@@ -1144,7 +1150,7 @@ def test_no_traversal_of_view_request_attribute(self):
 
 TEST_FILE_DATA = b'''
 --12345
-Content-Disposition: form-data; name="file"; filename="file"
+Content-Disposition: form-data; name="smallfile"; filename="smallfile"
 Content-Type: application/octet-stream
 
 test