Get migrate messages from correct database

I have a migration from a database that is not default.

I've set it up, as recommended and for performance reasons, to put the "map" tables in the source database. I've done this by adding the source database name as the last argument to the MigrateSQLMap constructor. This seems to mean that the "message" tables also get created in the source database.

If I get any messages during a migration, clicking in the link fails saying the relevant table doesn't exist. It's looking in the default database for the messages.