check netnsfd before closing
check netnsfd before closing

Signed-off-by: Serge Hallyn <3df611b026e4639bee8aef7a4beb2e39fcebb313@ubuntu.com>

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