From: Sascha Silbe <sascha-pgp@silbe.org>
Subject: [PATCH] rebuild index on migration (#1787)

Currently we force an index rescan on migration, but not a rebuild.
Any entry that's already in the index will _not_ be updated.
This patch fixes the migration logic to do a full index rebuild,
thus actually migrating the index.

Signed-off-by: Sascha Silbe <sascha-pgp@silbe.org>