Disable KVM at limestone (again)

There appears to be a kernel regression that is leading to KVM failures
again. This patch adds limestone to the exclusion list based on job
failures[1].

[1] http://logs.openstack.org/32/600332/3/check/octavia-v1-dsvm-scenario/ \
    467a1e6/logs/libvirt/qemu/instance-00000001.txt.gz

Change-Id: I91782536599fc28f2824a5dcc1483be46904ce56
diff --git a/playbooks/Octavia-DSVM/pre.yaml b/playbooks/Octavia-DSVM/pre.yaml
index 3ab7e20..9d6beb7 100644
--- a/playbooks/Octavia-DSVM/pre.yaml
+++ b/playbooks/Octavia-DSVM/pre.yaml
@@ -6,7 +6,7 @@
         cmd: |
           set -e
           set -x
-          if $(egrep --quiet '(vmx|svm)' /proc/cpuinfo) && [[ ! $(hostname) =~ "ovh" ]]; then
+          if $(egrep --quiet '(vmx|svm)' /proc/cpuinfo) && [[ ( ! $(hostname) =~ "ovh" && ! $(hostname) =~ "limestone" ) ]]; then
               export DEVSTACK_GATE_LIBVIRT_TYPE=kvm
           fi