In a discussion in #openstack-infra, mgagne reported that this problem is caused by https://github.com/openstack-dev/devstack/commit/7b63c5ec9e9aea54024105a6521a754efc9f9983 which changes the version of pip devstack installs. The newer version of pip apparently resolves dependencies differently from 1.4.1, which is the last version known to work.
In a discussion in #openstack-infra, mgagne reported that this problem is caused by https:/ /github. com/openstack- dev/devstack/ commit/ 7b63c5ec9e9aea5 4024105a6521a75 4efc9f9983 which changes the version of pip devstack installs. The newer version of pip apparently resolves dependencies differently from 1.4.1, which is the last version known to work.