[MERGE] Fix how cog.py is invoked on Windows

[Ian Clatworthy]

Ian Clatworthy has voted approve.
Status is now: Approved
Comment:
I'll merge this.

For details, see: 
http://bundlebuggy.aaronbentley.com/request/%3C48746597.0305560a.619b.fffff1d1%40mx.google.com%3E