Comment 9 for bug 2007827

Okay, attempt number 3! After another long dive into dpkg states, triggers, and the interactions around the kernel and initrd I think I've finally got a version that should:

1. Never install a kernel which isn't fully installed (unless --force is specified)

2. Avoids the race on waiting for a kernel to become fully installed during an apt run (when it discovers it's being asked to install a non-fully-installed kernel, it defers itself by retriggering)

3. Avoids duplicated runs (it does use the full version list from "linux-version list", but defers in the case that the latest isn't fully installed)

It's currently building the aforementioned PPA (https://launchpad.net/~waveform/+archive/ubuntu/flash-kernel) and the test procedure should be the same:

* Install a stock lunar preinstalled server image
* sudo add-apt-repository ppa:waveform/flash-kernel
* sudo apt install linux-xilinx-zynqmp flash-kernel
* Ensure that upgrade proceeds without error
* sudo reboot
* Ensure system boots with new kernel version (and initrd!) successfully

I've tested this several times with the raspi images (that displayed a related, but different symptom) in circumstances that do replicate the race condition without the fix and things are successful there, so I'm hoping that's also the case on Xilinx.