Better error message in example script
Better error message in example script

Change-Id: Icfbea6f47028accd3c976279e6eafdcb0b76b226

markon/pygerrit2,dpursehouse/pygerrit2,benjiii/pygerrit,dpursehouse/pygerrit,morucci/pygerrit,gferon/pygerrit2,sonyxperiadev/pygerrit