To clarify, this is the HDDIMG which has the initramfs based installer. The installer script has been replaced with a Mender-specific one. Basically, the Mender version of the HDDIMG includes the UEFIIMG and then just uses “dd” to write it. If MENDER_STORAGE_DEVICE is set, it will attempt to use that. Otherwise, if mender-partuuid is set, it will scan for appropriate devices.
That said, prior to the PR mentioned, the HDDIMG file would not work. Now “install” is the only boot option and it does work.