--- a/mercurial/hgweb/wsgicgi.py	Sun Feb 03 14:26:39 2013 -0800
+++ b/mercurial/hgweb/wsgicgi.py	Mon Feb 04 23:25:25 2013 +0100
@@ -77,5 +77,7 @@
     try:
         for chunk in content:
             write(chunk)
+        if not headers_sent:
+            write('')   # send headers now if body was empty
     finally:
         getattr(content, 'close', lambda : None)()