Test db_migrations doesn't work concurrently

[Joshua Hesketh]

When running with alternative test_migrations.conf odd errors occur.

For example, with just mysql tests often the database/tables disappear pre-maturely:

ProgrammingError: (ProgrammingError) (1146, "Table 'test_migrations.migrate_version' doesn't exist") 'SELECT migrate_version.repository_id, migrate_version.repository_path, migrate_version.version \nFROM migrate_version \nWHERE migrate_version.repository_id = %s' ('nova',)

With both sqlite and mysql it sometimes actually works. Possibly this is due to race conditions.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/40137

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/40137
Committed: http://github.com/openstack/nova/commit/cf99852f51f95bcf60c99df7190841ffff3337cb
Submitter: Jenkins
Branch: master

commit cf99852f51f95bcf60c99df7190841ffff3337cb
Author: Joshua Hesketh <email address hidden>
Date: Sat Aug 3 00:09:08 2013 +1000

    Fix tests to work with mysql+postgres concurrently

    Optimise tests.db.test_migrations and tests.db.test_migration_utils for
    concurrency and make opportunistic tests obey walk_style configurations.

    Closes-Bug: 1207750

    Change-Id: Idb30f144fb67aefc58749897d774103c3c0ec640