[PATCH] Use parsed subject for mboxes

[Stephen Finucane]

On Sat, 2018-04-07 at 17:44 +0100, Stephen Finucane wrote:
> With a recent change, we started using the original subject header
> instead of the one we had already cleaned up at the parsing stage.
> Revert this aspect of that change.
> 
> Signed-off-by: Stephen Finucane <stephen at that.guru>
> Fixes: 01b9cbb9 ("Include all email headers in mboxes")

This has broken the build so I've gone right ahead and merged it.

Stephen