[Dovecot] imap - file ioloop.c: line 22 (io_add): assertion failed: (fd >= 0)

[Wolfgang Fischer]

in dovecot 1.0RC13 after "Disconnected in IDLE"  I get following Error:

Nov 12 19:49:51 mini1 dovecot: IMAP(wolfgang): Disconnected in IDLE
Nov 12 19:49:51 mini1 dovecot: IMAP(wolfgang): file ioloop.c: line 22  
(io_add): assertion failed: (fd >= 0)
Nov 12 19:49:51 mini1 dovecot: child 1301 (imap) killed with signal 6

dovecot is running with Mac OS 10.4.8 (PowerPC), Mailbox Format is mbox.

Wolfgang