Perhaps it is documented elsewhere but I could not find a direct solution after googling few minutes. My u-boot partition was stuck at the same version on the nightly. I needed to fix the reboot issue. I've tried few things like apt upgrade or direct dpkg -i...
Anyway, this is what I did on a EMMC installation (/dev/mmcblk2) after I've built and download my own version of the package:
dpkg -i ./linux-u-boot-dev-orangepi3_5.86_arm64.deb
cat sunxi-spl.bin u-boot.itb > u-boot-sunxi-with-spl.bin
dd if=u-boot-sunxi-with-spl.bin of=/dev/mmcblk2 bs=1024 seek=8
I'm my case I had to unplug it and replug... (broken reboot). The new version is now installed : U-Boot 2019.04-armbian (May 11 2019 - 08:05:18 -0400)
Reboot works, and now it has a fixed mac addr (new feature).