X-OfflineIMAP prevents turning mails with several Gmail labels into hardlinks

[Iain Dalton]

I set up OfflineIMAP with Dovecot, so Gnus could access it (it has trouble
directly accessing maildirs). At first I had

    localfolders = ~/Archive/Mail

and downloaded everything. I was able to run hardlink -t[0] on the folder to
approximately halve its size. Then I deleted it and re-downloaded with

    preauthtunnel = /usr/sbin/dovecot --exec-mail imap

now every message has an X-OfflineIMAP header, which aren't the same on
identical messages, so hardlink doesn't work.

What's X-OfflineIMAP for, and can I get rid of it? I'm using 6.2.0.2ubuntu1
from Ubuntu 10.10, but I can use the git repo if that fixes my problem.

[0]: http://jak-linux.org/projects/hardlink/