Some openstack packages show up in the requirements list under a
hyphenated name while their package metadata name contains only
underscores. (For example, the glance_store library is listed in
requirements as 'glance-store'.) This is causing problems for the
tox_install_sibling_packages task run by zuul. Pip is able to handle
this situation [0]; add code so the ansible task can handle it too.
[0] http://paste.openstack.org/show/722298/
Change-Id: I89ad9926647a011174815761e79372f2d7d43609
Needed-by: https://review.openstack.org/#/c/569225/
Closes-bug: #1774030