Comment 4 for bug 321540

okay, did some more tracing. It seems that error exists in file:
http://archive.ubuntu.com/ubuntu/dists/jaunty/main/i18n/Translation-pl
description of packages cups-bsd and cups-common is incorrect - second line of description does not start with space. After I corrected these descriptions, update-apt-xapian-index works fine, and so does adept.

Well, now I guess it's not xapian's bug, but I have no idea whose is it.