Ticket searches may sometimes error out with "undefined field assigned_to", since searches grab one arbitrary ticket and call index() on it to determine what fields exist (to append _s etc to match solr naming). But index() on Ticket doesn't always include assigned_to_s.
Easiest way to reproduce is with a fresh data set (or db.ticket.remove({})) and then create a ticket without an owner. Then search for assigned_to:foo and get the error.
Fixed on
db/8069branch.Looks good :)