Issue #4718: Adapt the wsgiref package so that it actually works with Python 3.x,
in accordance with http://www.wsgi.org/wsgi/Amendments_1.0
diff --git a/Lib/wsgiref/util.py b/Lib/wsgiref/util.py
index 2686b66..937be60 100644
--- a/Lib/wsgiref/util.py
+++ b/Lib/wsgiref/util.py
@@ -149,8 +149,8 @@
     environ.setdefault('wsgi.multithread', 0)
     environ.setdefault('wsgi.multiprocess', 0)
 
-    from io import StringIO
-    environ.setdefault('wsgi.input', StringIO(""))
+    from io import StringIO, BytesIO
+    environ.setdefault('wsgi.input', BytesIO())
     environ.setdefault('wsgi.errors', StringIO())
     environ.setdefault('wsgi.url_scheme',guess_scheme(environ))