boto/boto — pull request #1213 by katzj (2012-12-31 07:48:01+00:00)
Title: Fix STS AssumeRole for third party delegation

For third party account delegation, you need to use the ExternalId parameter, not UniqueClientId according to the docs (and testing it out).

Adjust the paramter accordingly. Since this hasn't been in a released boto, I didn't think it was worth trying to keep compatibility with the old parameter name but can do so trivially if you'd rather