Restoring content doesn't work with a custom db prefix configured

[marijnvdwerf]

Describe the conversion bug
The post conversion can't be undone if the database prefix is not 'wp_'. The 'Restore' button simply has no effect, and the web inspector shows a DB error in the request.

Source of the error
The query contains a wp_postmeta literal, instead of getting the table name from $wpdb