/lib/udev/rules.d/60-multipath.rules is in multipath-tools 0.5.0-6+deb8u2.
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 8 | #
# udev rules for multipathing.
# The persistent symlinks are created with the kpartx rules
#
# Coalesce multipath devices before multipathd is running (initramfs, early
# boot)
ACTION=="add|change", SUBSYSTEM=="block", RUN+="/sbin/multipath -v0 /dev/$name"
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