"The revision being read has been discarded - you should call Xapian::Database::reopen() and retry the operation"

[Chris Down]

David Bremner writes:
>Very recent versions of xapian-check (1.3 +? not sure) have an option F to attempt to
>repair the database. That's about all I can think of. If you have a lot
>of effort in your metadata, you might ask on the xapian user list
><xapian-discuss at lists.xapian.org>.

Yeah, seems the version shipped with arch is still 1.2.22, presumably because 
it's marked as the "stable release". I might just build a newer version from 
source then, thanks for the tip. :-)

    % xapian-check --version
    xapian-check - xapian-core 1.2.22
    % xapian-check -F Mail/Personal/.notmuch/xapian
    option Mail/Personal/.notmuch/xapian unknown
    use t,f,b,v and/or + in the option string

I don't have much (read: any) effort in my metadata, so I guess I'll just 
rebuild from scratch.