Exception masked due to log exception

[Paul Michali]

In neutron/plugins/cisco/cfg_agent/device_drivers/driver_mgr.py, if an exception occurs loading the Cfg Agent, a log message is created and it causes a second exception due to incorrect key used to access template name.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/121197

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/121197
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=a2ef082cb0b25d14595a8810adb16df3f9661e43
Submitter: Jenkins
Branch: master

commit a2ef082cb0b25d14595a8810adb16df3f9661e43
Author: Paul Michali <email address hidden>
Date: Fri Sep 12 14:16:35 2014 -0400

    Access correct key for template name

    When an exception occurs while loading the config agent driver, the
    handler tries to log a message, but accesses the wrong key to get the
    template name. This causes another exception, which masks the original
    exception.

    This change accesses the correct key and performs logging inside a
    with block to (defensively) preserve the exception context.

    Change-Id: I3991bc4c509bbd8d68f7a1c8c8314404f2e0eafa
    Closes-Bug: #1368900