Block requests==2.9.0
Block requests==2.9.0

Because of https://bugs.launchpad.net/nova/+bug/1526413

Signed-off-by: Zack Cerza <d7cdf09fc0f0426e98c9978ee42da5d61fa54986@redhat.com>

dmick/teuthology,SUSE/teuthology,SUSE/teuthology,ktdreyer/teuthology,dmick/teuthology,SUSE/teuthology,dmick/teuthology,ceph/teuthology,ktdreyer/teuthology,ceph/teuthology