Why does the server hang during shutdown when iface eth0 inet dhcp is not physically connected?

Question

linux

There is a server under Debian wheezy, two network interfaces, only eth1 is physically connected.
In this configuration it works fine:
/etc/network/interfaces

auto lo
iface lo inet loopback
#auto eth0
#iface eth0 inet dhcp
auto eth1
iface eth1 inet dhcp

But if you uncomment eth0, then when loading the server it freezes for about a minute, DHCPDISCOVER attempts are visible in the logs. But this is all clear. Oddities occur when the server is turned off or restarted. As a result, you have to use the Reset button. The logs are empty, on the screen something like this (with minor gaps) output:

Deconfiguring Network Inrefaces...
Listening on LPF/eth1/...
Sending on LPF/eth1/...
Sending on Socket/fallback
DHCPRELEASE on eth1 to ...
...
Listening on LPF/eth0/...
Sending on LPF/eth0/...
Sending on Socket/fallback
[...] INFO: task ip:3707 blocked for more than 120 seconds.
[...] "echo 0 > /prpc/sys/kernel/hung_task_timeout_secs" disables...(край фотки обрезан)... message.