Error while using changes to applied alembic migrations scripts

[Artem Roma]

When changes are made to alembic revision script and that migration is already applied, second applying will not set the changes for database which could lead to different errors while interacting with db. Such situation can occur, for example, when in different git topics revisions with same uid but different content are stored. The issue mainly affects development process, particularly tests execution.

In order to resolve the problem we may need to perform cleaning of db schema before new tests execution. Such code is already present in nailgun infrastructure [1], so we need to include it to ostf and adapt it for the project.

[1]: https://github.com/stackforge/fuel-web/blob/d31b59a7ed9f1aade5bd73cc252b301b0a257733/nailgun/nailgun/db/sqlalchemy/__init__.py#L96-146

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/155290

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/155290
Committed: https://git.openstack.org/cgit/stackforge/fuel-ostf/commit/?id=f509330e00f6a04bd9ab9afd1923f1ab44aa839e
Submitter: Jenkins
Branch: master

commit f509330e00f6a04bd9ab9afd1923f1ab44aa839e
Author: Artem Roma <email address hidden>
Date: Thu Feb 12 14:48:11 2015 +0200

    Cleaning db before integration tests added

    Complete cleaning of db schema added before execution of integration
    tests. The main reason of introducing such cleaning - issue with
    applying alembic revisions with same uid but different content that are
    stored in different git branches, which leads to erros while interaction
    with db.

    Change-Id: I94611015beb4dd83d036b813c9337958dc6af064
    Closes-Bug: #1421164