I have noticed that when building a clean system build will proceed to download the kernel via ftp and when the transfer is complete and the control connection closes it will assume that it failed to download it and proceed to download the very same thing via http. Is there a reason for this behaviour ?

i wouldn't know anything about your bug reporting system so that's why I'm using the forum to post this "bug" untill I get a bit more into openwrt development tools etc, sorry.