dovecot - Aug 2008 - imap crash with signal 6 (backtrace), dovecot 1.1.2

GNU gdb 6.8-debian
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
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This GDB was configured as "i486-linux-gnu"...
Reading symbols from /lib/i686/cmov/libdl.so.2...Reading symbols from
/usr/lib/debug/lib/i686/cmov/libdl-2.7.so...done.
done.
Loaded symbols for /lib/i686/cmov/libdl.so.2
Reading symbols from /lib/i686/cmov/libc.so.6...Reading symbols from
/usr/lib/debug/lib/i686/cmov/libc-2.7.so...done.
done.
Loaded symbols for /lib/i686/cmov/libc.so.6
Reading symbols from /lib/ld-linux.so.2...Reading symbols from
/usr/lib/debug/lib/ld-2.7.so...done.
done.
Loaded symbols for /lib/ld-linux.so.2
Reading symbols from /usr/local/lib/dovecot/imap/lib10_quota_plugin.so...done.
Loaded symbols for /usr/local/lib/dovecot/imap/lib10_quota_plugin.so
Reading symbols from
/usr/local/lib/dovecot/imap/lib11_imap_quota_plugin.so...done.
Loaded symbols for /usr/local/lib/dovecot/imap/lib11_imap_quota_plugin.so
Reading symbols from /usr/local/lib/dovecot/imap/lib11_trash_plugin.so...done.
Loaded symbols for /usr/local/lib/dovecot/imap/lib11_trash_plugin.so
Reading symbols from /usr/local/lib/dovecot/imap/lib20_fts_plugin.so...done.
Loaded symbols for /usr/local/lib/dovecot/imap/lib20_fts_plugin.so
Reading symbols from
/usr/local/lib/dovecot/imap/lib20_mail_log_plugin.so...done.
Loaded symbols for /usr/local/lib/dovecot/imap/lib20_mail_log_plugin.so
Reading symbols from
/usr/local/lib/dovecot/imap/lib21_fts_squat_plugin.so...done.
Loaded symbols for /usr/local/lib/dovecot/imap/lib21_fts_squat_plugin.so
Reading symbols from /usr/lib/gconv/ISO8859-1.so...Reading symbols from
/usr/lib/debug/usr/lib/gconv/ISO8859-1.so...done.
done.
Loaded symbols for /usr/lib/gconv/ISO8859-1.so
Reading symbols from /lib/libgcc_s.so.1...done.
Loaded symbols for /lib/libgcc_s.so.1
Core was generated by `/usr/local/libexec/dovecot/imap'.
Program terminated with signal 6, Aborted.
[New process 20506]
#0  0xb8009424 in __kernel_vsyscall ()
#0  0xb8009424 in __kernel_vsyscall ()
#1  0xb7eca640 in raise () from /lib/i686/cmov/libc.so.6
#2  0xb7ecc018 in abort () from /lib/i686/cmov/libc.so.6
#3  0x080d5ef5 in default_fatal_finish (type=<value optimized out>,
status=0)
    at failures.c:149
#4  0x080d5f62 in i_internal_fatal_handler (type=LOG_TYPE_PANIC, status=0, 
    fmt=0x80e98ac "file %s: line %d (%s): assertion failed: (%s)", 
    args=0xbf922a24 "?r\017\b\204") at failures.c:423
#5  0x080d5919 in i_panic (
    format=0x80e98ac "file %s: line %d (%s): assertion failed: (%s)")
    at failures.c:190
#6  0x080c4746 in get_ext_header (map=<value optimized out>, 
    ext=<value optimized out>) at mail-index-sync-ext.c:131
#7  0x080c47a2 in mail_index_sync_ext_reset (ctx=0xbf922b80, u=0xbf922af0)
    at mail-index-sync-ext.c:524
#8  0x080b65f9 in mail_index_sync_record (ctx=0xbf922b80, hdr=0x986c970, 
    data=0x98ad860) at mail-index-sync-update.c:546
#9  0x080b6bef in mail_index_sync_map (_map=0x986cb88, 
    type=MAIL_INDEX_SYNC_HANDLER_FILE, force=false)
    at mail-index-sync-update.c:828
#10 0x080b04b4 in mail_index_map (index=0x986cb50, 
    type=MAIL_INDEX_SYNC_HANDLER_FILE) at mail-index-map.c:932
#11 0x080b4802 in mail_index_sync_commit (_ctx=0x984d32c)
    at mail-index-sync.c:755
#12 0x08074169 in maildir_sync_index_finish (_ctx=0x98280ec, failed=false, 
    cancel=false) at maildir-sync-index.c:248
#13 0x08072ea3 in maildir_sync_context (ctx=0x98280d0, 
    forced=<value optimized out>, find_uid=0x0, lost_files_r=0xbf922e5b)
    at maildir-sync.c:795
#14 0x08073038 in maildir_storage_sync_init (box=0x984e9e8, flags=65)
    at maildir-sync.c:859
#15 0x080a49a9 in mailbox_sync (box=0x984e9e8, flags=0, status_items=111, 
    status_r=0xbf922ec8) at mail-storage.c:509
#16 0x08060ce8 in cmd_select_full (cmd=0x98345f0, readonly=false)
    at cmd-select.c:39
#17 0x08060ea9 in cmd_select (cmd=0x98345f0) at cmd-select.c:88
#18 0x0806276c in client_command_input (cmd=0x98345f0) at client.c:580
#19 0x08062803 in client_command_input (cmd=0x98345f0) at client.c:629
#20 0x08062dbd in client_handle_input (client=<value optimized out>)
    at client.c:670
#21 0x0806323e in client_input (client=0x98343a8) at client.c:725
#22 0x080dd8d0 in io_loop_handler_run (ioloop=0x98309b0) at ioloop-epoll.c:203
#23 0x080dcd40 in io_loop_run (ioloop=0x98309b0) at ioloop.c:320
#24 0x0806b3aa in main (argc=) at main.c:293