Sync rpc from oslo.

Sync some trivial Python 3 compatibility and pep8 improvements from oslo.
I just want to have this in sync so that pulling in a feature I'm working
on comes in without unrelated changes

Change-Id: I13fcb0bd538a153b90acf0b18497e335a64dc9d1
Merge "Sync rpc from oslo."
Merge remote-tracking branch 'm_src_repo/citrix-fixes' into build-temp