boto/boto — pull request #777 by cosmin (2012-05-23 03:42:23+00:00)
Title: Allow modifying instance security groups (needed for VPC)

allow modifying security groups via instance.modify_attribute and modify_instance_attribute. In order to accomplish this it was necessary to switch to the new calling format for ModifyInstanceAttribute. Also, add groupSet to the documentation for instance.get_attribute and get_instance_attribute

http://docs.amazonwebservices.com/AWSEC2/latest/APIReference/ApiReference-query-ModifyInstanceAttribute.html

I also found the pull request https://github.com/boto/boto/pull/723 that uses the new calling convention but does not handle the security groups modification.