Comment 3 for bug 1037201

Reviewed: https://review.openstack.org/11420
Committed: http://github.com/openstack/nova/commit/00f0b170ec15299b20c345fa1f66f21185c2dc79
Submitter: Jenkins
Branch: master

commit 00f0b170ec15299b20c345fa1f66f21185c2dc79
Author: Dan Prince <email address hidden>
Date: Wed Aug 15 13:07:19 2012 -0400

    Update disk config to check for 'server' in req.

    Updates the disk config extension to check for 'server' in the
    request body before trying to use it. This avoids a potential
    KeyError exception. Given that we already validate the 'server'
    dict in servers.py and raise a proper exception there this seems
    reasonable to me... no reason to duplicate all of the validation
    logic.

    The reason this change was able to make it into Nova to begin
    with is that the Extensions loader orders things differently
    depending on the OS/python version being used. I tested this
    by running SchedulerHintsTestCase.test_create_missing_server
    on both Fedora 16 (passes) and Fedora 17 (fails). The problem
    only manifests itself when the disk config extension gets called
    before the scheduler_hints extension. To fix this issue
    I've updated the scheduler_hints extensions in this patchset
    to simply pass when 'server' isn't defined which like above seems
    reasonable because we already validate this in servers.py.

    As part of this fix I'm also moving test_create_missing_server out
    of the Scheduler Hints tests and into a new ServersAllExtensionsTestCase
    class in test_servers.py which explicitly tests for things with *all*
    extensions enabled. As part of the move I also updated the test to
    look for HTTP 422 Unprocessable Entity which is what we throw when
    'server' doesn't exist in a POST to servers (the correct exception).

    Fixes LP Bug #1037201.

    Change-Id: I912fc1234b2e7a76ecc54140f4a31c2e32fdfa98