diff --git a/mercurial/hgweb/wsgicgi.py b/mercurial/hgweb/wsgicgi.py
new file mode 100644
--- /dev/null
+++ b/mercurial/hgweb/wsgicgi.py
@@ -0,0 +1,69 @@
+# hgweb/wsgicgi.py - CGI->WSGI translator
+#
+# Copyright 2006 Eric Hopper <hopper@omnifarious.org>
+#
+# This software may be used and distributed according to the terms
+# of the GNU General Public License, incorporated herein by reference.
+#
+# This was originally copied from the public domain code at
+# http://www.python.org/dev/peps/pep-0333/#the-server-gateway-side
+
+import os, sys
+
+def launch(application):
+
+    environ = dict(os.environ.items())
+    environ['wsgi.input']        = sys.stdin
+    environ['wsgi.errors']       = sys.stderr
+    environ['wsgi.version']      = (1,0)
+    environ['wsgi.multithread']  = False
+    environ['wsgi.multiprocess'] = True
+    environ['wsgi.run_once']    = True
+
+    if environ.get('HTTPS','off') in ('on','1'):
+        environ['wsgi.url_scheme'] = 'https'
+    else:
+        environ['wsgi.url_scheme'] = 'http'
+
+    headers_set = []
+    headers_sent = []
+
+    def write(data):
+        if not headers_set:
+             raise AssertionError("write() before start_response()")
+
+        elif not headers_sent:
+             # Before the first output, send the stored headers
+             status, response_headers = headers_sent[:] = headers_set
+             sys.stdout.write('Status: %s\r\n' % status)
+             for header in response_headers:
+                 sys.stdout.write('%s: %s\r\n' % header)
+             sys.stdout.write('\r\n')
+
+        sys.stdout.write(data)
+        sys.stdout.flush()
+
+    def start_response(status,response_headers,exc_info=None):
+        if exc_info:
+            try:
+                if headers_sent:
+                    # Re-raise original exception if headers sent
+                    raise exc_info[0], exc_info[1], exc_info[2]
+            finally:
+                exc_info = None     # avoid dangling circular ref
+        elif headers_set:
+            raise AssertionError("Headers already set!")
+
+        headers_set[:] = [status,response_headers]
+        return write
+
+    result = application(environ, start_response)
+    try:
+        for data in result:
+            if data:    # don't send headers until body appears
+                write(data)
+        if not headers_sent:
+            write('')   # send headers now if body was empty
+    finally:
+        if hasattr(result,'close'):
+            result.close()