/lib/udev/vlan-network-interface is in vlan 1.9-3.2ubuntu1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 | #!/bin/sh
# vlan-network-interface - configure a network bridge
#
# This service checks whether a physical network device that has been added
# has VLAN defined in /etc/network/interfaces that should be brought up
set -e
if [ -z "$INTERFACE" ]; then
    echo "missing \$INTERFACE" >&2
    exit 1
fi
if ! which ifquery >/dev/null; then
    exit 0
fi
if [ ! -x /etc/network/if-pre-up.d/vlan ]; then
    exit 0
fi
mkdir -p /run/network
for IFACE in $(ifquery --list --allow auto); do
    IF_VLAN_RAW_DEVICE=$(ifquery $IFACE | sed -n -e's/^vlan[_-]raw[_-]device: //p')
    # Now that the environment is ready, call the pre-up script to create the vlan
    export IFACE IF_VLAN_RAW_DEVICE
    # Create the VLANs related to the interface
    if [ "$IF_VLAN_RAW_DEVICE" = "$INTERFACE" ] || \
        echo $IFACE | grep -q $INTERFACE; then
            /etc/network/if-pre-up.d/vlan
    fi
done
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