IntegrityError: columns ticket, time, field are not unique

[mcepl]

I hope even the Czech version of the backtrace is readable (Soubor is File, řádek is line, v is in)

Soubor "/usr/lib/python2.6/site-packages/trac/web/main.py", řádek 525, v _dispatch_request
  dispatcher.dispatch(req)
Soubor "/usr/lib/python2.6/site-packages/trac/web/main.py", řádek 246, v dispatch
  resp = chosen_handler.process_request(req)
Soubor "/usr/lib/python2.6/site-packages/trac/ticket/web_ui.py", řádek 170, v process_request
  return self._process_newticket_request(req)
Soubor "/usr/lib/python2.6/site-packages/trac/ticket/web_ui.py", řádek 398, v _process_newticket_request
  self._do_create(req, ticket) # (redirected if successful)
Soubor "/usr/lib/python2.6/site-packages/trac/ticket/web_ui.py", řádek 1193, v _do_create
  ticket.insert()
Soubor "/usr/lib/python2.6/site-packages/trac/ticket/model.py", řádek 246, v insert
  listener.ticket_created(self)
Soubor "/srv/trac/desktopqe-backlog/plugins/TracTicketRelationsPlugin-1.0.3-py2.6.egg/ticketrelations/api.py", řádek 46, v ticket_created
  self.ticket_changed(tkt, '', tkt['reporter'], {})
Soubor "/srv/trac/desktopqe-backlog/plugins/TracTicketRelationsPlugin-1.0.3-py2.6.egg/ticketrelations/api.py", řádek 60, v ticket_changed
  links.save(old_relations, author, comment, tkt.time_changed, db)
Soubor "/srv/trac/desktopqe-backlog/plugins/TracTicketRelationsPlugin-1.0.3-py2.6.egg/ticketrelations/model.py", řádek 46, v save
  self.update_relations(k, v, author, comment, when_ts, db)
Soubor "/srv/trac/desktopqe-backlog/plugins/TracTicketRelationsPlugin-1.0.3-py2.6.egg/ticketrelations/model.py", řádek 80, v update_relations
  (n, when_ts, author, field, old_value, new_value))
Soubor "/usr/lib/python2.6/site-packages/trac/db/util.py", řádek 65, v execute
  return self.cursor.execute(sql_escape_percent(sql), args)
Soubor "/usr/lib/python2.6/site-packages/trac/db/sqlite_backend.py", řádek 78, v execute
  result = PyFormatCursor.execute(self, *args)
Soubor "/usr/lib/python2.6/site-packages/trac/db/sqlite_backend.py", řádek 56, v execute
  args or [])
Soubor "/usr/lib/python2.6/site-packages/trac/db/sqlite_backend.py", řádek 48, v _rollback_on_error
  return function(self, *args, **kwargs)

System information

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:20.0) Gecko/20.0 Firefox/20.0
Trac    0.12.3
Babel   0.9.4
Genshi  0.6
GIT     1.7.1
mod_python  3.3.1
pysqlite    2.4.1
Python  2.6.6 (r266:84292, Aug 28 2012, 10:55:56) [GCC 4.4.6 20120305 (Red Hat 4.4.6-4)]
RPC     1.1.2
setuptools  0.6
SQLite  3.6.20
Subversion  1.6.11 (r934486)
jQuery  1.4.4