The firmware from Jessie/OMV image is apparently from the official Linux firmware repository, which has not been updated in quite a while.
https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/tree/brcm
The firmware from Raspbian/Stretch has been updated specifically to fix Broadpwn:
Running "strings" on the Raspbian brcmfmac43430-sdio.bin shows:
Which interestingly does not exactly match your dmesg message. In any case, this is obviously the one we should use. If it works. Which I have no idea.
