Tweak to notebook -> .py export, at Fernando's suggestion.

IPython/nbformat/v2/nbpy.py

@@ -113,8 +113,8 b' class PyReader(NotebookReader):'
 class PyWriter(NotebookWriter):
 
     def writes(self, nb, **kwargs):
-        lines = []
-        lines.extend([u'# coding: utf-8', u'# <nbformat>2</nbformat>',''])
+        lines = [u'# coding: utf-8']
+        lines.extend([u'# <nbformat>2</nbformat>',''])
         for ws in nb.worksheets:
             for cell in ws.cells:
                 if cell.cell_type == u'code':