linux_net fails to start dnsmasq as root

The command to start dnsmasq has some bash environment prefixes (FLAGFILE=, NETWORK_ID=) but the call to execute isn't marked with shell=True. So when "Make nova-rootwrap optional" got merged (Change-Id: I2cf5c743c6f4d6f235a54ca70c11d8191deeed6a) instead of always prefixing the commandline with "sudo" - if you're running as root (as I do on some automated dev/test/build vms) - the commandline now started with "FLAGFILE" and subprocess throws a OSError/ENOENT because there's no executable with that name ;)

2012-10-30 12:17:57 DEBUG nova.utils [req-7dc40cb3-8410-4868-927c-1b5d50ede910 None None] Running cmd (subprocess): FLAGFILE=/etc/nova/nova.conf NETWORK_ID=1
 dnsmasq --strict-order --bind-interfaces --conf-file= --domain=novalocal --pid-file=/etc/nova/state/networks/nova-virbr0.pid --listen-address=10.0.0.1 --exc
ept-interface=lo --dhcp-range=set:'private',10.0.0.2,static,120s --dhcp-lease-max=256 --dhcp-hostsfile=/etc/nova/state/networks/nova-virbr0.conf --dhcp-scrip
t=/opt/nova/bin/nova-dhcpbridge --leasefile-ro execute /opt/nova/nova/utils.py:171
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/eventlet/hubs/hub.py", line 336, in fire_timers
    timer()
  File "/usr/local/lib/python2.7/dist-packages/eventlet/hubs/timer.py", line 56, in __call__
    cb(*args, **kw)
  File "/usr/local/lib/python2.7/dist-packages/eventlet/greenthread.py", line 192, in main
    result = function(*args, **kwargs)
  File "/opt/nova/nova/service.py", line 123, in run_server
    server.start()
  File "/opt/nova/nova/service.py", line 389, in start
    self.manager.init_host()
  File "/opt/nova/nova/network/manager.py", line 1943, in init_host
    super(FlatDHCPManager, self).init_host()
  File "/opt/nova/nova/network/manager.py", line 889, in init_host
    self._setup_network_on_host(ctxt, network)
  File "/opt/nova/nova/network/manager.py", line 1954, in _setup_network_on_host
    self.driver.update_dhcp(context, dev, network)
  File "/opt/nova/nova/network/linux_net.py", line 772, in update_dhcp
    restart_dhcp(context, dev, network_ref)
  File "/opt/nova/nova/openstack/common/lockutils.py", line 229, in inner
    retval = f(*args, **kwargs)
  File "/opt/nova/nova/network/linux_net.py", line 858, in restart_dhcp
    _execute(*cmd, run_as_root=True)
  File "/opt/nova/nova/network/linux_net.py", line 950, in _execute
    return utils.execute(*cmd, **kwargs)
  File "/opt/nova/nova/utils.py", line 179, in execute
    shell=shell)
  File "/usr/local/lib/python2.7/dist-packages/eventlet/green/subprocess.py", line 25, in __init__
    subprocess_orig.Popen.__init__(self, args, 0, *argss, **kwds)
  File "/usr/lib/python2.7/subprocess.py", line 679, in __init__
    errread, errwrite)
  File "/usr/lib/python2.7/subprocess.py", line 1249, in _execute_child
    raise child_exception
OSError: [Errno 2] No such file or directory

It was a little hard to track down, because obviously running on the commandline works. It only happens on the boxes where I'm running services as root. And subprocess wasn't being really specific about what exactly it couldn't find :P

I looked for precedent adding shell=True to the call, but it seems the nova codebase prefers to explicitly set the environ with the env command.