Migration #33 doesn't work well with SQLite

[Ivan Kolodyazhny]

I hope, nobody uses SQLite not for unit-tests only. It is reproducible with SQLite only.

    /home/e0ne/src/openstack/cinder/.venv/local/lib/python2.7/site-packages/migrate/changeset/constraint.py:85: SAWarning: Table 'encryption' specifies columns 'volume_type_id' as primary_key=True, not matching locally specified columns 'encryption_id'; setting the current primary key columns to 'encryption_id'. This warning may become an exception in a future release
      self._set_parent(table)

We need to fix this warning before it will an error

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/165403

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/165403
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=5f8a616b15b70ddba6a64689b547521c91b95c84
Submitter: Jenkins
Branch: master

commit 5f8a616b15b70ddba6a64689b547521c91b95c84
Author: Anton Arefiev <email address hidden>
Date: Wed Mar 18 14:59:59 2015 +0200

    Fix 033 add encryption unique key migration

    SQLite doesn't support 'drop constraint' statament. So it notifies:
    SAWarning: Table 'encryption' specifies columns 'volume_type_id'
    as primary_key=True, not matching locally specified columns
    'encryption_id'; setting the current primary key columns to
    'encryption_id'. This warning may become an exception in a future
    release.

    Add new strategy for sqlite upgrade: table is renamed to temporary
    name, new table is created followed by INSERT statements, and
    renamed to original one.

    Change-Id: I723fdadb946f6944dde03954409899a9ddc3ee0e
    Closes-Bug: #1431374