Schema update hook uses drupal_get_schema_unprocessed()

drupal_get_schema_unprocessed() should not be used in schema update hooks. In the event that the schema changes in the future, the update hook from the past will load the newest schema and operate with that when it is expecting to use an older "snapshot."

The solution is to make a copy of the schema definition in the update hook so there is a snapshot of what the schema looked like at a given point in time.

This is still fixable now, but will quickly become critical if the schema changes.