This patch solves the immediate failure:

Index: Lib/locale.py
===================================================================
--- Lib/locale.py	(revision 85743)
+++ Lib/locale.py	(working copy)
@@ -396,6 +396,9 @@
         else:
             encoding = defenc
         #print 'found encoding %r' % encoding
+        if sys.platform == 'darwin' and encoding == 'UTF8':
+            encoding = 'UTF-8'
+
         if encoding:
             return langname + '.' + encoding
         else:

I'm not happy about hardcoding this specific exception though, there should be a better solution than this.

Ronald