neutron-rootwrap-xen-dom0 does not handle stdin

[Amir Sadoughi]

To reproduce:

http://paste.openstack.org/show/54794/

I used Ctrl-D (EOF) on a new line to end input, but it did not respond.

The netwrap process was still running in the dom0 after I Ctrl-C'd.

```
[root@xen ~]# ps aux | grep netwrap
root 9987 0.0 0.6 8664 4840 ? Ss 03:27 0:00 python /etc/xapi.d/plugins/netwrap <methodCall><methodName>run_command</methodName><params><param><value>OpaqueRef:c4567826-fa48-c815-2de8-dbb97bad01cd</value></param><param><value><struct><member><name>cmd</name><value>[&quot;ovs-ofctl&quot;, &quot;add-flows&quot;, &quot;fake-br&quot;, &quot;-&quot;]</value></member></struct></value></param></params></methodCall>
root 11234 0.0 0.0 4896 716 pts/1 S+ 03:29 0:00 grep netwrap
[root@xen ~]# kill 9987
```

I originally encountered this bug working on blueprint ovs-firewall-driver by invoking neutron/agent/linux/ovs_lib.py:OvsBridge.defer_apply_off. I have a feasible workaround for now by avoiding use of stdin.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/62346

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/62346
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=6cc8bd73ac24c0cb4b9cbe3d7961584ea0322d01
Submitter: Jenkins
Branch: master

commit 6cc8bd73ac24c0cb4b9cbe3d7961584ea0322d01
Author: Simon Pasquier <email address hidden>
Date: Mon Dec 16 13:43:38 2013 +0100

    neutron-rootwrap-xen-dom0 handles data from stdin

    The neutron-rootwrap-xen-dom0 script and the netwrap plugin have been
    modified to pass stdin from one to the other.

    Change-Id: Ie97980873ed95f2c96eb68f8de611de1a733b130
    Closes-Bug: #1259748