duplicate 'global_filter' created by function set_lvm_filter

[Sam Wan]

function set_lvm_filter in https://github.com/openstack-dev/devstack/tree/master/lib only creates 'global_filter' but not removes existing one which causes below warnings:
WARNING: Ignoring duplicate config node: global_filter (seeking global_filter)

Fix is simple.
Just insert below line before setting 'global_filter' in set_lvm_filter to remove any existing 'global_filter':
sudo sed -ir '/^\s*global_filter.*$/d' /etc/lvm/lvm.conf

or use below line to comment out any existing global_filter by:
sudo sed -ir 's/^\s*(global_filter.*)$/#\1/g' /etc/lvm/lvm.conf

[Sam Wan (sam-wan)]

i've submitted a review https://review.openstack.org/#/c/176222/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/176889
Committed: https://git.openstack.org/cgit/openstack-dev/devstack/commit/?id=6cdb2e0f1a2c2429587f1e9187344cb26eb31812
Submitter: Jenkins
Branch: master

commit 6cdb2e0f1a2c2429587f1e9187344cb26eb31812
Author: Dan Smith <email address hidden>
Date: Thu Apr 23 09:12:59 2015 -0700

    Remove the lvm.conf filter during cleanup

    This avoids us leaving the filter in the global lvm config. Without cleaning
    this up, we can hit some failures to run stack.sh because devices are excluded
    that we need to be able to see. This resets it to what it was before when
    we do a cleanup.

    Also, do this before we add the line, so we don't add multiple lines on
    successive runs.

    Closes-bug: #1437998
    Change-Id: Idbf8a06b723f79ef16a7c175ee77a8c25f813244

[OpenStack Infra (hudson-openstack)]

Change abandoned by Sam Wan (<email address hidden>) on branch: master
Review: https://review.openstack.org/176222

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/kilo
Review: https://review.openstack.org/182385

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/182385
Committed: https://git.openstack.org/cgit/openstack-dev/devstack/commit/?id=2d4ea363aeb059939cf0947a54acd19ac4e9d3b0
Submitter: Jenkins
Branch: stable/kilo

commit 2d4ea363aeb059939cf0947a54acd19ac4e9d3b0
Author: Dan Smith <email address hidden>
Date: Thu Apr 23 09:12:59 2015 -0700

    Remove the lvm.conf filter during cleanup

    This avoids us leaving the filter in the global lvm config. Without cleaning
    this up, we can hit some failures to run stack.sh because devices are excluded
    that we need to be able to see. This resets it to what it was before when
    we do a cleanup.

    Also, do this before we add the line, so we don't add multiple lines on
    successive runs.

    Closes-bug: #1437998
    Change-Id: Idbf8a06b723f79ef16a7c175ee77a8c25f813244
    (cherry picked from commit 6cdb2e0f1a2c2429587f1e9187344cb26eb31812)