/lib/udev/rules.d/60-zpool.rules is in zfs-initramfs 0.6.5.6-0ubuntu8.
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 | # This creates symlinks directly in /dev with the same names as those in
# /dev/disk/by-id, but only for ZFS partitions. This is necessary for GRUB to
# https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1527727
# https://bugs.launchpad.net/ubuntu/+source/zfs-initramfs/+bug/1530953
# locate the partitions using the output of `zpool status`.
KERNEL=="sd*[0-9]", IMPORT{parent}=="ID_*", ENV{ID_PART_ENTRY_SCHEME}=="gpt", ENV{ID_PART_ENTRY_TYPE}=="6a898cc3-1dd2-11b2-99a6-080020736631", SYMLINK+="$env{ID_BUS}-$env{ID_SERIAL}-part%n"
KERNEL=="sd*[0-9]", IMPORT{parent}=="ID_*", ENV{ID_FS_TYPE}=="zfs_member", ENV{ID_FS_USAGE}=="raid", SYMLINK+="$env{ID_BUS}-$env{ID_SERIAL}-part%n"
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