[Dovecot] Folder name migration when moving from 2.0.x to 2.1.x?

[Ralf Hildebrandt]

Today I encountered this after upgrading:

Feb 18 18:15:40 postamt dovecot: imap(lehnertr): Panic: LIST: Mailbox name not UTF-8: INBOX.Entw�rfe
Feb 18 18:15:40 postamt dovecot: imap(lehnertr): Error: Raw backtrace:
/usr/local/lib/dovecot/libdovecot.so.0(+0x4104a) [0xb75cc04a] ->
/usr/local/lib/dovecot/libdovecot.so.0(+0x410bb) [0xb75cc0bb] ->
/usr/local/lib/dovecot/libdovecot.so.0(i_fatal+0) [0xb75cc9b7] ->
dovecot/imap [lehnertr 85.178.5.225 LSUB]() [0x8052bac] ->
dovecot/imap [lehnertr 85.178.5.225 LSUB](cmd_list_full+0x4af)
[0x80530df] -> dovecot/imap [lehnertr 85.178.5.225
LSUB](cmd_lsub+0x17) [0x8053537] -> dovecot/imap [lehnertr
85.178.5.225 LSUB](command_exec+0x32) [0x8057c92] -> dovecot/imap
[lehnertr 85.178.5.225 LSUB]() [0x8056c7d] -> dovecot/imap [lehnertr
85.178.5.225 LSUB]() [0x8056d95] -> dovecot/imap [lehnertr
85.178.5.225 LSUB](client_handle_input+0x135) [0x8056fa5] ->
dovecot/imap [lehnertr 85.178.5.225 LSUB](client_input+0x60)
[0x80578a0] ->
/usr/local/lib/dovecot/libdovecot.so.0(io_loop_call_io+0x44)
[0xb75dafb4] ->
/usr/local/lib/dovecot/libdovecot.so.0(io_loop_handler_run+0xce)
[0xb75dbe5e] -> /usr/local/lib/dovecot/libdovecot.so.0

a) It should not PANIC (I think)
b) How can I globally "fix" the folder names (preferably in such a way
   that I am able to switch back and forth between 2.0 and 2.1)
-- 
Ralf Hildebrandt
  Geschäftsbereich IT | Abteilung Netzwerk
  Charité - Universitätsmedizin Berlin
  Campus Benjamin Franklin
  Hindenburgdamm 30 | D-12203 Berlin
  Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962
  ralf.hildebrandt at charite.de | http://www.charite.de