Netcfg and allow-hotplug vs auto

["Matheus Morais" <matheus.morais@gmail.com>]

I've been with this doubt a couple months but just now I found some time to comment about it.
I've customized some parts of debian-installer and I always still facing the same issue. netcfg module is responsible to write /etc/network/interfaces at installation time right? Why use allow-hotplug instead auto in network configuration file? 
Currently if I use allow-hotplug and configure that ethernet as dhcp client, always when the machine reboots the eth0 interface is downed so I need to set it up manually using 'dhclient eth0' by the command line. When I change 'allow-hotplug' to 'auto' at network/interfaces everything works perfectly. I adapt my netcfg module to always install interfaces with 'auto' option, since I dont know how to figure this problem out. Anyone know why this happen?

Thanks in advance,
Matheus Morais