Comment 3 for bug 775192

This looks fine to me now. Can you still reproduce this?

$ zsync http://releases.ubuntu.com/natty/ubuntu-11.04-desktop-i386.iso.zsync
#################### 100.0% 214.6 kBps DONE

No relevent local data found - I will be downloading the whole file. If that's not what you want, CTRL-C out. You should specify the local file is the old version of the file to download with -i (you might have to decompress it with gzip -d first). Or perhaps you just have no data that helps download the file
downloading from http://releases.ubuntu.com/natty/ubuntu-11.04-desktop-i386.iso:
-------------------- 0.3% 270.7 kBps 44:09 ETA