No exception message when libvirt is not installed

[Miguel Alejandro Cantu]

The _get_ext_mgr defines a callback method[1] that is invoked when stevedore has a problem loading a module.
The exception message should be logged if ceilometer ever reaches this point. Right now it's very ambiguous to just have the "Skip loading extension for" message come up every time a module fails to load.

[1]https://github.com/openstack/ceilometer/blob/master/ceilometer/agent/manager.py#L288-L290

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/253120

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/253120
Committed: https://git.openstack.org/cgit/openstack/ceilometer/commit/?id=68cdac1b1f25a7a008515b4b9f158fbb49f78e72
Submitter: Jenkins
Branch: master

commit 68cdac1b1f25a7a008515b4b9f158fbb49f78e72
Author: Miguel Alex Cantu <email address hidden>
Date: Thu Dec 3 18:08:39 2015 +0000

    Log exception if stevedore fails to load module

    This commit logs the exception thrown by stevedore
    if ceilometer ever reaches this point.

    Change-Id: I6613bd0e26cdda0007ace996b5de65ed60fc5cf3
    Closes-Bug: #1522521

[Thierry Carrez (ttx)]

This issue was fixed in the openstack/ceilometer 6.0.0.0b2 development milestone.