boto/boto — pull request #1384 by Sovietaced (2013-03-13 03:25:50+00:00)
Title: Fixed parameter type for attach_network_interfaces

Real simple fix, the device index is supposed to be sent as a string, not an integer. I was getting parameter errors from the ec2 api and tried it out with a string in ec2-api-tools and it worked.

proof here : http://docs.aws.amazon.com/AWSEC2/latest/CommandLineReference/ApiReference-cmd-AttachNetworkInterface.html