imap(hardy): Panic: file istream-tee.c: line 138 (i_stream_tee_read): assertion failed: (last_high_offset == input->v_offset + size)

[Hardy Flor]

Hello,

I'm copy with imapsync (on the new server with dovecot) with a single 
user all mails from a old server to the new server.

The error-message ist after 20-30 minutes in the log, and I must restart 
the imapsync. The next mail is normal store on the destination box.

Hardy