Added a test for the restore_hazards procedure

I have added this test for documentation purposes, since it is easy to forget how the restore_hazards script works exactly. In particular the value of the sequence id is always set to the maximum id value in the table, which may be higher than the id in the file. This is to avoid future id clashes: if the sequence id was set to the maximum value in the file, and that value was lower than the some other id in the table, then if one keeps inserting new  rows a clash would be inevitable.