installer: Honor --post again
installer: Honor --post again

This is a way to inject external data into the interactive kickstart
path.  It's used by RHEL Atomic Host to change the origin file.

projectatomic/rpm-ostree-toolbox,markllama/rpm-ostree-toolbox,sujitfulse/rpm-ostree-toolbox,projectatomic/rpm-ostree-toolbox,markllama/rpm-ostree-toolbox,tlitovsk/rpm-ostree-toolbox,projectatomic/rpm-ostree-toolbox,maxamillion/rpm-ostree-toolbox,projectatomic/rpm-ostree-toolbox,maxamillion/rpm-ostree-toolbox,sujitfulse/rpm-ostree-toolbox,maxamillion/rpm-ostree-toolbox,tlitovsk/rpm-ostree-toolbox,tlitovsk/rpm-ostree-toolbox,tlitovsk/rpm-ostree-toolbox,markllama/rpm-ostree-toolbox,giuseppe/rpm-ostree-toolbox,projectatomic/rpm-ostree-toolbox,maxamillion/rpm-ostree-toolbox,sujitfulse/rpm-ostree-toolbox,sujitfulse/rpm-ostree-toolbox,markllama/rpm-ostree-toolbox,markllama/rpm-ostree-toolbox,sujitfulse/rpm-ostree-toolbox,markllama/rpm-ostree-toolbox,maxamillion/rpm-ostree-toolbox,sujitfulse/rpm-ostree-toolbox,giuseppe/rpm-ostree-toolbox,giuseppe/rpm-ostree-toolbox,tlitovsk/rpm-ostree-toolbox,tlitovsk/rpm-ostree-toolbox,giuseppe/rpm-ostree-toolbox,maxamillion/rpm-ostree-toolbox,giuseppe/rpm-ostree-toolbox,giuseppe/rpm-ostree-toolbox