fix for dump headers

Subject: fix for dump headers

Date: Tue, 28 Mar 2017 08:09:01 -0300



From: David Bremner

When I added message properties to the dump output I messed up the
copy-paste to add properties to the header. The fix is trivial, but
I'm not sure if this means we should bump the format version
(i.e. write #notmuch-dump:3) to denote the header can be relied
upon. I guess it doesn't hurt to do so. Opinions?