Debian stretch

[gizag]

fair warning to all: the current way xbian does mirror selection breaks apt 1.4 (the new apt used in stretch)

I've spend more than 1 headbreaking hour trying to fix the issue (being misdirected due to it being similar to an old bug reported elsewhere)

The following workaround works:
edit /etc/apt/sources.list.d/xbian.list and change the mirror:// part into http:// (httpS might work, not tested) and remove the mirror.txt at the end.
Or better, to not overload the server, open the mirror.txt file in your browser and randomly choose a mirror and copy the url in the right place.