Hi,

Section 5.2.1 of Debian Handbook suggests that wicd might conflict with
ifup, and hence advise to keep the file /etc/network/interfaces as
simple as possible, such as

auto lo
iface lo inet loopback

or disable wicd and let ifup do the work. Perhaps the default
/etc/network/interfaces should be changed?

-- My /etc/network/interfaces:
source /etc/network/interfaces.d/*

auto lo
iface lo inet loopback

allow-hotplug eth0
iface eth0 inet dhcp
iface eth0 inet6 auto