util: fix bad variable use in bytecount introduced by f0f7f3fab315 stable

util: fix bad variable use in bytecount introduced by f0f7f3fab315

--- a/mercurial/util.py	Mon May 21 16:32:50 2012 -0500
+++ b/mercurial/util.py	Mon May 21 14:24:24 2012 -0500
@@ -1186,7 +1186,7 @@
     for multiplier, divisor, format in _byteunits:
         if nbytes >= divisor * multiplier:
             return format % (nbytes / float(divisor))
-    return units[-1][2] % nbytes
+    return _byteunits[-1][2] % nbytes
 
 def uirepr(s):
     # Avoid double backslash in Windows path repr()