2.3.3: Panic: file ostream-zlib.c: line 37 (o_stream_zlib_close): assertion failed

[Tom Sommer]

I see this in my logs after 2.3.3:

using zlib plugin, ofc.

Oct 02 10:01:39 imap(user at example.com)<50643></2k4Sjp3vMqC496W>: Panic: 
file ostream-zlib.c: line 37 (o_stream_zlib_close): assertion failed: 
(zstream->ostream.finished || zstream->ostream.ostream.stream_errno != 0 
|| zstream->ostream.error_handling_disabled)
Oct 02 10:01:39 imap(user at example.com)<50643></2k4Sjp3vMqC496W>: Error: 
Raw backtrace: /usr/lib64/dovecot/libdovecot.so.0(+0xce56a) 
[0x7f442487556a] -> /usr/lib64/dovecot/libdovecot.so.0(+0xce5b1) 
[0x7f44248755b1] -> /usr/lib64/dovecot/libdovecot.so.0(+0x3d941) 
[0x7f44247e4941] -> /usr/lib64/dovecot/lib20_zlib_plugin.so(+0x5cdf) 
[0x7f44233c4cdf] -> /usr/lib64/dovecot/libdovecot.so.0(+0xf4b46) 
[0x7f442489bb46] -> 
/usr/lib64/dovecot/libdovecot.so.0(o_stream_destroy+0x13) 
[0x7f442489be83] -> 
/usr/lib64/dovecot/libdovecot-storage.so.0(maildir_save_finish+0x173) 
[0x7f4424b93973] -> 
/usr/lib64/dovecot/libdovecot-storage.so.0(mailbox_save_cancel+0x36) 
[0x7f4424b68696] -> dovecot/imap [user at example.com X.X.X.X 
APPEND](+0xede9) [0x55a9d7e86de9] -> dovecot/imap [user at example.com 
X.X.X.X APPEND](command_exec+0x65) [0x55a9d7e956e5] -> dovecot/imap 
[user at example.com X.X.X.X APPEND](+0xf9e6) [0x55a9d7e879e6] -> 
/usr/lib64/dovecot/libdovecot.so.0(io_loop_call_io+0x55) 
[0x7f442488c275] -> 
/usr/lib64/dovecot/libdovecot.so.0(io_loop_handler_run_internal+0xbf) 
[0x7f442488e13f] -> 
/usr/lib64/dovecot/libdovecot.so.0(io_loop_handler_run+0x55) 
[0x7f442488c365] -> /usr/lib64/dovecot/libdovecot.so.0(io_loop_run+0x38) 
[0x7f442488c588] -> 
/usr/lib64/dovecot/libdovecot.so.0(master_service_run+0x13) 
[0x7f4424808053] -> dovecot/imap [user at example.com X.X.X.X 
APPEND](main+0x32d) [0x55a9d7ea20dd] -> 
/lib64/libc.so.6(__libc_start_main+0x100) [0x7f4424431d20] -> 
dovecot/imap [user at example.com X.X.X.X APPEND](+0xe419) [0x55a9d7e86419]

No clue how to reproduce


-- 
Tom