diff -r d89f80898178 -r 27b080aa880a mercurial/sslutil.py
--- a/mercurial/sslutil.py	Fri Jun 17 15:43:50 2011 -0500
+++ b/mercurial/sslutil.py	Sat Jun 18 01:03:03 2011 +0200
@@ -48,7 +48,8 @@
         for name in certnames:
             if matchdnsname(name):
                 return None
-        return _('certificate is for %s') % ', '.join(certnames)
+        if certnames:
+            return _('certificate is for %s') % ', '.join(certnames)
 
     # subject is only checked when subjectAltName is empty
     for s in cert.get('subject', []):