Comment 4 for bug 1300628

Reviewed: https://review.openstack.org/84983
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=1997cc97f14b95251ad568820160405e34a39801
Submitter: Jenkins
Branch: master

commit 1997cc97f14b95251ad568820160405e34a39801
Author: Kevin Benton <email address hidden>
Date: Thu Apr 3 10:00:37 2014 +0000

    BigSwitch: Don't import portbindings_db until use

    The Big Switch ML2 driver re-uses large parts of
    code from the Big Switch plugin. However, the plugin
    uses the old portbindings_db in its port tracking
    code. This db is not created/used by ML2, so it does
    not exist when the Big Switch ML2 driver is being used.
    This caused a problem when the portbindings_db module
    would be imported even though it wasn't being used
    since the SQLAlchemy models would create the
    relationships during the import.

    This patch moves the portbindings_db import down to
    the methods that leverage it so it won't be imported
    during use by the ML2 driver.

    This is a temporary solution which can be back-ported
    if disabling auto schema generation is back-ported
    to icehouse. An appropriate fix will require some
    refactoring to avoid the port tracking code from
    being imported for ML2.

    Closes-Bug: #1300628
    Change-Id: I551abf9d6ec832c423cba0d50bb27715b43c0b1c