Comment 3 for bug 1665370

Ok so further testing this may be packaging related, as I ended up with two versions of python-nova installed:

[root@overcloud-controller-0 ~]# rpm -ql python-nova | grep migrate_repo | grep "py$" | grep 021
/usr/lib/python2.7/site-packages/nova/db/sqlalchemy/api_migrations/migrate_repo/versions/021_build_requests_instance_mediumtext.py
/usr/lib/python2.7/site-packages/nova/db/sqlalchemy/api_migrations/migrate_repo/versions/021_placeholder.py
[root@overcloud-controller-0 ~]# rpm -qa | grep python-nova
python-nova-15.0.0-0.20170215034806.bdeb05d.el7.centos.noarch
python-nova-14.0.4-0.20170117154931.c6743ca.el7.centos.noarch
[root@overcloud-controller-0 ~]# rpm -qf /usr/lib/python2.7/site-packages/nova/db/sqlalchemy/api_migrations/migrate_repo/versions/021_build_requests_instance_mediumtext.py
python-nova-14.0.4-0.20170117154931.c6743ca.el7.centos.noarch
[root@overcloud-controller-0 ~]# rpm -qf /usr/lib/python2.7/site-packages/nova/db/sqlalchemy/api_migrations/migrate_repo/versions/021_placeholder.py
python-nova-15.0.0-0.20170215034806.bdeb05d.el7.centos.noarch

It's not yet clear how that happened, but I'll remove nova from this since it appears to be an issue specific to package updates and/or the tripleo upgrade workflow (in particular I think we can end up in this state if an upgrade fails during the package upgrade, then the upgrade is re-attempted).