I found the exact cause after reading the source code long enough. It tried to allocate too many inodes, pushing the first zone > 65536 blocks. This fails hard due to integer roundoff.
Therefore, workaround: mkfs.minix -3 -i#### specifying a more reasonable number of inodes will allow the filesystem to be created. -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org