/lib/udev/rules.d/75-probe_mtd.rules is in udev 232-25+deb9u8.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 | # do not edit this file, it will be overwritten on update
ACTION!="add", GOTO="mtd_probe_end"
KERNEL=="mtd*ro", IMPORT{program}="mtd_probe $devnode"
LABEL="mtd_probe_end"
|