Sync from oslo db.sqlalchemy.migration

Sync the updated migration module to prevent errors on non-utf8
migrate_version and alembic_version tables (not controlled by the
schema migration directory).

Change from oslo commits:
[2fd457bf2cc] Ignore migrate versioning tables in utf8 sanity check

Change-Id: I6aef126b8d09c7a44f3815c4143ef1d4e5463426
Closes-Bug: #1301036
Merge "Sync from oslo db.sqlalchemy.migration" into milestone-proposed