Comment 3 for bug 1070559

Reviewed: https://review.openstack.org/14714
Committed: http://github.com/openstack/nova/commit/5f3c2f9b8ea24b2a0e1909dbeac4dc47f2410d7a
Submitter: Jenkins
Branch: master

commit 5f3c2f9b8ea24b2a0e1909dbeac4dc47f2410d7a
Author: Rick Harris <email address hidden>
Date: Tue Oct 23 21:55:59 2012 +0000

    More specific exception handling in migration 091.

    The original code would catch and discard any exception generated when
    trying to create or drop fkey constraints using the SQLite engine. This
    has the side-effect of allowing the DB to become inconsistent (by
    leaving a `migration_tmp` table around), causing future migrations to
    fail and making bugs even hard to track down.

    Long term, we should fix the underlying cause of these exceptions,
    either by switching to Alembic or by fixing SQLALchemy-Migrate to fully
    support dropping of constraints via a temp table.

    For now though, tightening up the exception handling will at least make
    any future bugs a bit easier to diagnose.

    Fixes bug 1070559

    Change-Id: If549d65afa758b6f8a0db6fc8478a5b0c9277e23