[Dovecot] imap abort after upgrade from 2.2.4 to 2.2.7

[morrison]

Hi,

I used to use dovecot 2.2.4. I saw lots of warnings saying 'Extension header 
update points outside header size'.
I upgraded to dovecot 2.2.7, based on the discussion in mail list. Now, I see 
lots of imap aborts around:

    src/lib-index/mail-index-transaction-export.c:203:      i_assert(u32.offset 
+ u32.size <= ext_hdr_size);

I also noticed, in some mailbox, imap process kept abort until all index files 
in the mailbox were manually deleted.

Did someone run into the same problem and any solution to this?

Thanks,