Comment 22 for bug 461156

> Note that python-boto does encode UserData using base64.b64encode
> (not urlsafe_b64encode as suggested in comment 13).

Thierry is correct. The commenter in comment 13 above must have been staring at a computer screen too long. boto uses base64.b64encode everywhere that i can see: http://code.google.com/p/boto/source/browse/trunk/boto/ec2/connection.py .