Only mod image for test if necessary
Only mod image for test if necessary

Review URL: http://codereview.chromium.org/1606004

smilart/scripts,gtank/scripts,crawford/scripts,smilart/scripts,BugRoger/scripts,nicescale/scripts,endocode/scripts,endocode/scripts,mjg59/scripts,trnubo/scripts,glevand/coreos--scripts,vmware/coreos-scripts,glevand/coreos--scripts,marineam/coreos-scripts,andrejro/coreos--scripts,nicescale/scripts,zhang0137/scripts,coreos/scripts,crawford/scripts,sigma/coreos-scripts,andrejro/coreos--scripts,bcwaldon/coreos-scripts,smilart/scripts,trnubo/scripts,fivethreeo/scripts,gtank/scripts,sigma/coreos-scripts,bcwaldon/coreos-scripts,trnubo/scripts,fivethreeo/scripts,marineam/coreos-scripts,BugRoger/scripts,mischief/scripts,coreos/scripts,sigma/coreos-scripts,marineam/coreos-scripts,BugRoger/scripts,vmware/coreos-scripts,mjg59/scripts,bcwaldon/coreos-scripts,andrejro/coreos--scripts,endocode/scripts,zhang0137/scripts,mischief/scripts,gtank/scripts,mischief/scripts,mjg59/scripts,vmware/coreos-scripts,crawford/scripts,nicescale/scripts,zhang0137/scripts,fivethreeo/scripts