feather-m0: make flash reports "device unsupported"

[miri64]

Description

When trying to flash hello-world to BOARD=feather-m0, bossa (the default programmer for that board) reports Device unsupported.

Steps to reproduce the issue

With the respective board plugged into USB, run

BOARD=feather-m0 make -C examples/hello-world flash

Expected results

The hello world application should be flashed to the board.

Actual results

Flashing fails with

/home/mlenders/Repositories/RIOT-OS/RIOT/dist/tools/bossa-1.9/bossac -p /dev/ttyACM0 -o 0x2000 -e -i -w -v -b -R /home/mlenders/Repositories/RIOT-OS/RIOT/examples/hello-world/bin/feather-m0/hello-world.bin

Device unsupported
make: *** [/home/mlenders/Repositories/RIOT-OS/RIOT/examples/hello-world/../../Makefile.include:796: flash] Error 1

Versions

Current master (a17ff53) and definitely since 2021.10. I tried earlier releases, but they require cherry-picking 8f10f22, with cherry-picking I hit another merge-conflict wall in the 2020er releases, so I stopped there... I am pretty sure, that I was able to flash this board in early 2020 though.

[dylad]

I don't own the board and I am not using bossac since quite some time.
But if you still have access to it, could you try:
BOSSA_FLAGS_OPTS="-i -d" BOARD=feather-m0 make -C examples/hello-world flash
This might help to figure out what's going here.