boto/boto — pull request #2486 by piotrbulinski (2014-08-01 11:22:13+00:00)
Title: fix TypeError when getting instance metadata under python 3 (#2485)

It seems that every call in boto/utils.py expects string instead of bytes from the retry_url call, so I've fixed it there.
That should be easier than migrating all the code around to be py2/py3 compatible.

Solves the issue: #2485 for me.