fts-lucene with virtual folders

Hi,

It looks like I've found something strange. It looks like dovecot updates fts-lucene index every time I'm opening virtual folder that contains FTS query:

indexer-worker(dion): Warning: fts-lucene: Settings have changed, rebuilding index for mailbox

dovecot-virtual is pretty simple:

archive/INBOX
	BODY "test"

first of all, I'm trying to perform FTS in archive/INBOX itself, then I'm trying to open virtual folder.

both default namespace and 'archive' are private namespaces with mdbox storage.

plugin { fts = lucene fts_lucene = whitespace_chars=@. fts_autoindex = no }

Any suggestions?

-- WBR, Dmitry