[Dovecot] crash (assertion failed: (uidlist->lock_count == 1)

[Jakob Hirsch]

Hi,

with 1.0-test79

Aug  3 16:18:23 ymmv dovecot: IMAP(jh): file maildir-uidlist.c: line 536
(maildir_uidlist_rewrite): assertion failed: (uidlist->lock_count == 1)
Aug  3 16:18:23 ymmv dovecot: child 10780 (imap) killed with signal 6

Any idea what that is? I did no special operation, just selected a mail
to read with thunderbird (1.06). After restarting TB it worked.