I got the following with mbox and test-60:

Jan 12 20:11:17 ser dovecot: IMAP(juergen): file mail-index-transaction.c: line 57 (mail_keyword_transaction_free): assertion failed: (kt->keywords->kt == NULL) Jan 12 20:11:17 ser dovecot: child 24762 (imap) killed with signal 6

but only if I try to move/copy a larger number of messages, around >30, from on folder to another.

MUA: mutt, no other problems so far.

Greetings Juergen

-- Juergen Daubert | mailto:jue@jue.li
Korb, Germany | http://jue.li/crux