Bug#684996: calendarserver: not building with both python-2.6 and python-2.7 installed

[Rahul Amaram]

This patch excludes the "debian" directory in a safe way. I will push it 
in the next update.
Fix for building package for both python 2.6 and python 2.7. Thanks to Fredrik Unger for providing this patch.
--- a/setup.py
+++ b/setup.py
@@ -37,6 +37,7 @@
 
         if root == ".":
             excludes.append("data")
+            excludes.append("debian")
 
         for exclude in excludes:
             if exclude in dirs: