flash-kernel/preboot.d/00reform2_preboot: even if ${fdtfile} is set, use...
flash-kernel/preboot.d/00reform2_preboot: even if {fdtfile} is set, use dtb-
{fk_kvers} if it exists
We need to set ${fdtfile} in uboot to select a default dtb for boot mediums that are supposed to boot on multiple devices like the Debian installer.
But if ${fdtfile} is set, then bootscr.uboot-generic will use that instead of the dtb-${fk_kvers} symlink maintained by flash-kernel which will point to either the normal or the hdmi dtb for the reform.
This preboot script overwrites ${fdtpath} such that even when ${fdtfile} is set to a reasonable default, u-boot will still use dtb-${fk_kvers} if it exists -- which it does with sysimage-v3 after running flash-kernel.