Unnecessary database access by l3 agent

[Gary Kotton]

When running unit tests the test test_l3_agent_routers_query_ignore_interfaces_with_moreThanOneIp indicates unncesary database access.

/home/garyk/quantum/.tox/py27/local/lib/python2.7/site-packages/sqlalchemy/sql/expression.py:1927: SAWarning: The IN-predicate on "subnets.id" was invoked with an empty sequence. This results in a contradiction, which nonetheless can be expensive to evaluate. Consider alternative strategies for improved performance.
  return self._in_impl(operators.in_op, operators.notin_op, other)

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/17745

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/17745
Committed: http://github.com/openstack/quantum/commit/2e043a5a785b452f8f7fcb104b12c0746ca4a513
Submitter: Jenkins
Branch: master

commit 2e043a5a785b452f8f7fcb104b12c0746ca4a513
Author: Gary Kotton <email address hidden>
Date: Sun Dec 9 06:33:13 2012 +0000

    Prevent unnecessary database read by l3 agent

    Fixes bug 1088129

    Change-Id: I887facf321f3267c16c101a1448827f6c046bb2c