Use clearer error message on failure to create pidfile
Use clearer error message on failure to create pidfile

As suggested by Serge Hallyn on lxc-devel.

Signed-off-by: Stéphane Graber <089afc6d81f66f1168a9849e15660feae286e024@ubuntu.com>

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