west flash doesn't use merged.hex when using HEX_FILES_TO_MERGE

[0e4ef622]

For context, I'm working with an nRF5340 and I'm using Zephyr for the net core, while the app core is built externally. I have my CMakeLists.txt set up to build both and using the HEX_FILES_TO_MERGE property to create a merged.hex file, but when I run west flash it only flashes zephyr.hex, not merged.hex. It seems like in the commit that introduced this feature, west flash would handle it but perhaps that got lost somewhere?

I also noticed the "Adding non-Zephyr applications to sysbuild" in the docs, but it says "west flash or west debug will not be aware of the application" so that doesn't seem any better.

Is this a bug? Or is there another way to accomplish this? I know I can just do west flash --hex-file build/zephyr/merged.hex, but would be nice if west flash just worked.