Hello,

>> ice-9/boot-9.scm:1669:16: In procedure raise-exception:
>> ERROR:
>>   1. &i/o-filename: "/dev/disk/by-id/mmc-SDU64_0xbaf3002e"
>
> Thanks for testing. This is probably a regression in
> "write-file-on-device" that fails to open this kind of files. I'll try
> to reproduce it locally.

This is because the O_EXCL flag was passed, which causes open to fail if
the block device is mounted.

The revised patch attached should fix it.

Thanks,

Mathieu