block retrying 1.3.0

retrying 1.3.0 released ... without a requirements.txt even though
their setup.py thinks it should have one. They symptom is that glance
fails to install, and glance-manage doesn't exist.

Why pip install doesn't err early, will be a morning exercise.

Change-Id: Icd61ef2f33a250f0fcbcb583a1de46babb590a18
Fixes: the gate