fog/fog — pull request #1940 by adamjt (2013-07-03 20:18:47+00:00)
Title: Signature method requires x-amz-security-token header.

Before this change, when making requests to S3 on an instance using IAM role credentials I would receive that the signature was bad. While tracing the string_to_sign vs what AWS expected, I found that this header was missing.