Prevent Zope from sending "hop-by-hop" headers in WSGI responses

According to PEP 333, WSGI applications and middleware are forbidden from
using HTTP/1.1 "hop-by-hop" features or headers.

product/ERP5Type/ZopePatch.py

@@ -21,6 +21,7 @@
 ##############################################################################
 
 # Load all monkey patches
+from Products.ERP5Type.patches import backports
 from Products.ERP5Type.patches import HTTPRequest
 from Products.ERP5Type.patches import AccessControl_patch
 from Products.ERP5Type.patches import Restricted

product/ERP5Type/patches/backports.py

+##############################################################################
+#
+# Copyright (c) 2002 Zope Foundation and Contributors.
+#
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE.
+#
+##############################################################################
+
+from ZPublisher.WSGIPublisher import WSGIResponse
+
+# PATCH 1
+#
+# According to PEP 333, WSGI applications and middleware are forbidden from
+# using HTTP/1.1 "hop-by-hop" features or headers. This patch prevents Zope
+# from sending 'Connection' and 'Transfer-Encoding' headers.
+#
+# The following code is a backport from Zope 4.0b1, see commit
+# be5b14bd858da787c41a39e2533b0aabcd246fd5.
+def finalize(self):
+
+    headers = self.headers
+    body = self.body
+
+    # set 204 (no content) status if 200 and response is empty
+    # and not streaming
+    if ('content-type' not in headers and
+            'content-length' not in headers and
+            not self._streaming and self.status == 200):
+        self.setStatus('nocontent')
+
+    # add content length if not streaming
+    content_length = headers.get('content-length')
+
+    if content_length is None and not self._streaming:
+        self.setHeader('content-length', len(body))
+
+    return '%s %s' % (self.status, self.errmsg), self.listHeaders()
+
+WSGIResponse.finalize = finalize