isc-dhcp server not use configuration file options

[Viacheslav Kaloshin]

in /etc/default/isc-dhcp-server describe two options
# cat /etc/default/isc-dhcp-server
....
# On what interfaces should the DHCP server (dhcpd) serve DHCP requests?
# Separate multiple interfaces with spaces, e.g. "eth0 eth1".
INTERFACESv4=""
INTERFACESv6=""

But in systemctl unit files used old option, without v4/v6 suffixes

# systemctl cat isc-dhcp-server6.service
.....
    exec dhcpd -user dhcpd -group dhcpd -f -6 -pf /run/dhcp-server/dhcpd6.pid -cf $CONFIG_FILE $INTERFACES'

Fix is very quick ;)

s/INTERFACES/INTERFACESv4/ in isc-dhcp-server.service
s/INTERFACES/INTERFACESv6/ in isc-dhcp-server6.service

Or as workaround add old INTERFACES="" to /etc/default/isc-dhcp-server

ProblemType: Bug
DistroRelease: Ubuntu 19.10
Package: isc-dhcp-server 4.4.1-2ubuntu5
ProcVersionSignature: Ubuntu 5.3.0-26.28-generic 5.3.13
Uname: Linux 5.3.0-26-generic x86_64
ApportVersion: 2.20.11-0ubuntu8.2
Architecture: amd64
Date: Wed Jan 22 12:51:26 2020
InstallationDate: Installed on 2020-01-18 (3 days ago)
InstallationMedia: Ubuntu-Server 19.10 "Eoan Ermine" - Release amd64 (20191017)
ProcEnviron:
 SHELL=/bin/bash
 LANG=en_US.UTF-8
 TERM=xterm-256color
 PATH=(custom, no user)
SourcePackage: isc-dhcp
UpgradeStatus: No upgrade log present (probably fresh install)
modified.conffile..etc.dhcp.dhcpd.conf: [modified]
modified.conffile..etc.dhcp.dhcpd6.conf: [modified]
mtime.conffile..etc.dhcp.dhcpd.conf: 2020-01-19T14:25:59.040443
mtime.conffile..etc.dhcp.dhcpd6.conf: 2020-01-19T16:28:31.017125

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.