HS hsid's become mismatched when "add another item" on a filefield is clicked on.

Steps to reproduce:

1. Create a node type that has a filefield, set "Number of Values" to "Unlimited"
2. Create a taxonomy vocab and terms which uses hierarchy select turned on.
3. Create a new content of that node type.
4. Go to the file field on the node form and click "Add another item." (doesn't matter if you have a file selected in the first file item or not)
5. Click on the taxonomy drop down and select a term.

We then get this JS error:

Drupal.settings.HierarchicalSelect.settings[_hsid] is undefined /sites/all/modules/hierarchical_select/hierarchical_select.js?M
Line 279

After debugging that line, I found that the hsid indexes within the Drupal.settings.HierarchicalSelect.settings array no longer match what's within the form. Probably due to some change that happened during the AHAH callback when there's a filefield element addition.