fix(build_image): Always use read-write for developer images.
fix(build_image): Always use read-write for developer images.

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