feature support matrix docs build fails with misleading error

[Matt Riedemann]

The docs job kept failing on this patch:

https://review.openstack.org/#/c/454322/24

With this error:

http://logs.openstack.org/22/454322/24/check/gate-nova-docs-ubuntu-xenial/62d7b0a/console.html#_2017-07-05_16_18_34_699873

Exception: 'libvirt-vz-ct' missing in '[operation.extend-volume]' section

But that driver is in the patch:

https://review.openstack.org/#/c/454322/24/doc/source/support-matrix.ini

The problem was the powervm impl was missing, but there is a bug in the support matrix parsing code such that when it failed, it put the wrong driver target key in the error message, so it was misleading.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/480708

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/480708
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=9269d35ea876fa54edb9b332e927ee9d73c40f50
Submitter: Jenkins
Branch: master

commit 9269d35ea876fa54edb9b332e927ee9d73c40f50
Author: Matt Riedemann <email address hidden>
Date: Wed Jul 5 15:15:50 2017 -0400

    Fix error message when support matrix entry is missing a driver

    This was noticed in change If10cffd0dc4c9879f6754ce39bee5fae1d04f474
    which was missing the powervm driver target for the extend-volume entry.

    Before this change, the error message was:

      'libvirt-vz-ct' missing in '[operation.extend-volume]' section

    This was really confusing because that driver is in the change. What
    was missing was powervm, but because the error message is using the
    wrong key that was not showing up.

    Change-Id: I2e7ea49d5ba42cc633796222af47c1d4cd59f96b
    Closes-Bug: #1702542

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/nova 16.0.0.0b3 development milestone.