Address the comments of the merged image handler patch

Three minor things which was commented in change:
Idce8d21ae37bfdbb28a2567120a83d1061061904

Change-Id: Idd899ec2c177c9b5695b6908bc897fe3e759beca
Signed-off-by: Zhi Yan Liu <zhiyanl@cn.ibm.com>
Merge "Address the comments of the merged image handler patch"