Rewrite X-IMAPbase: header before updating index file header, so that we write the latest mtime as sync_stamp.
Rewrite X-IMAPbase: header before updating index file header, so that we
write the latest mtime as sync_stamp.

--HG--
branch : HEAD

dscho/dovecot,dscho/dovecot,dscho/dovecot,dscho/dovecot,dscho/dovecot