Comment 9 for bug 1436957

Keystone has custom test tools [0] for this (which are named the same and slightly confusing). The one assertRaisesRegexp test tool was added [1] as a fix for py26 and is not the same as the function from python 2. It might be useful to change the name of [0] to avoid any future confusion, but for the purpose of this bug, keystone shouldn't need any changes.

[0] https://github.com/openstack/keystone/blob/7754f170aa0eb42bea356e7f912bc241832eb1f3/keystone/tests/unit/core.py#L800
[1] https://review.openstack.org/#/c/39064/