be856ef968
consider a out-of-range partition letter at the end of the special device node to be a fatal error; just return NULL and let the caller fall back to FFS. This fixes the "mount -u /kern/rootdev /" done by the script installer. XXX this is still gross, and breaks things like "mount /my/strange/dev/path/b /mnt". Perhaps it should stat the node and use the minor number as an index instead?