[Dovecot] dovecot 2.0.beta6 dies when I try to delete a folder with thunderbird

[Sven Kirmess]

When I try to delete a folder with Thunderbird 3.1 I get the following
log entry and the folder is not deleted. Filesystem is ZFS.

Jun 27 15:32:36 azati dovecot: [ID 583609 mail.error] master: Error:
service(imap): child 18215 killed with signal 11 (core not dumped -
set drop_priv_before_exec=yes)
Jun 27 15:32:36 azati dovecot: [ID 583609 mail.error] master: Error:
service(imap): child 18213 killed with signal 11 (core not dumped -
set drop_priv_before_exec=yes)

# 2.0.beta6: /etc/opt/dovecot/dovecot/dovecot.conf
# OS: SunOS 5.10 i86pc  zfs
first_valid_uid = 100
mail_location = mdbox:/l/dovecot/%u/dbox
namespace {
  inbox = yes
  location =
  prefix =
  separator = /
  type = private
}
passdb {
  driver = pam
}
protocols = imap
service imap-login {
  inet_listener imap {
    port = 0
  }
}
service imap {
  vsz_limit = 1073741824
}
ssl = required
ssl_cert = </etc/opt/dovecot/dovecot/certs/dovecot.pem
ssl_key = </etc/opt/dovecot/dovecot/private/dovecot.pem
userdb {
  driver = passwd
}
verbose_proctitle = yes