lxc-user-nic: be more paranoid
lxc-user-nic: be more paranoid

Just setting path isn't enough.  Clear the whole environment, and only set
$PATH.  It's all we need - ovs-vsctl is running fine this way.

Signed-off-by: Serge Hallyn <3df611b026e4639bee8aef7a4beb2e39fcebb313@ubuntu.com>
Acked-by: Stéphane Graber <089afc6d81f66f1168a9849e15660feae286e024@ubuntu.com>

terceiro/lxc,major/lxc,lisongmin/lxc,JohnPeacockMessageSystems/lxc,hfuCN/lxc,ecarrara/lxc,yubo/lxc,Pelagicore/lxc,fwilson42/lxc,hkjolhede/lxc,ysbnim/lxc,akshaykarle/lxc,caglar10ur/lxc,hkjolhede/lxc,thmo/lxc,bmoar/lxc,QingweiPeterLan/cs188-lxc,hallyn/lxc,bmoar/lxc,regit/lxc,jirislaby/lxc,GreatFruitOmsk/lxc,DarknessBeforeDawn/lxc,major/lxc,efiop/lxc,terceiro/lxc,szaszg/lxc,codebauss/lxc,Ponce/lxc,hkjolhede/lxc,cjwatson/lxc,armcc/lxc,aeris/lxc,sapun/lxc,Distrotech/lxc,lazy404/lxc,GreatFruitOmsk/lxc,weizhenwei/lxc,tych0/lxc,weizhenwei/lxc,Distrotech/lxc,armcc/lxc,raspberrypython/lxc,rldleblanc/lxc,Ponce/lxc,JohnPeacockMessageSystems/lxc,aeris/lxc,bostjan/lxc,rowhit/lxc,caglar10ur/lxc,ss1h2a3tw/lxc,Pelagicore/lxc,virajs/lxc,raspberrypython/lxc,ksperis/lxc,ysbnim/lxc,rowhit/lxc,hfuCN/lxc,hfuCN/lxc,efiop/lxc,ysbnim/lxc,lisongmin/lxc,terceiro/lxc,jirislaby/lxc,codebauss/lxc,rowhit/lxc,major/lxc,virajs/lxc,szaszg/lxc,JohnPeacockMessageSystems/lxc,yubo/lxc,hallyn/lxc,caglar10ur/lxc,ioops/lxc,thmo/lxc,rldleblanc/lxc,ecarrara/lxc,Ponce/lxc,christiaan/lxc,thmo/lxc,bmoar/lxc,sapun/lxc,federicobriata/lxc,federicobriata/lxc,virajs/lxc,ksperis/lxc,regit/lxc,armcc/lxc,raspberrypython/lxc,bostjan/lxc,codebauss/lxc,akshaykarle/lxc,aeris/lxc,ss1h2a3tw/lxc,lazy404/lxc,tych0/lxc,lazy404/lxc,Pelagicore/lxc,efiop/lxc,DarknessBeforeDawn/lxc,federicobriata/lxc,rldleblanc/lxc,hallyn/lxc,sapun/lxc,bostjan/lxc,LynxChaus/lxc,ioops/lxc,QingweiPeterLan/cs188-lxc,LynxChaus/lxc,ecarrara/lxc,cjwatson/lxc,LynxChaus/lxc,christiaan/lxc,yubo/lxc,fwilson42/lxc,lisongmin/lxc,christiaan/lxc,tych0/lxc,ksperis/lxc,regit/lxc,jirislaby/lxc,cjwatson/lxc,fwilson42/lxc,weizhenwei/lxc,Distrotech/lxc,GreatFruitOmsk/lxc,akshaykarle/lxc,ss1h2a3tw/lxc,DarknessBeforeDawn/lxc,ioops/lxc,szaszg/lxc,QingweiPeterLan/cs188-lxc