uc_store_site_id contains invalid information

uc_store_send_report() sends an HTTP POST to http://www.ubercart.org/statistics/report, but this URL currently returns a 404 page rather than a site ID string. This results in a full HTML page being stored in the uc_store_site_id variable. A sanity check should probably be added to uc_store_send_report() that only saves the site ID if a 32-character string was returned by ubercart.org.

This can be reproduced by visiting /admin/store/settings/store/edit/report and ensuring the "Report version information" checkbox is checked, deleting the uc_store_last_report variable, running cron, and revisiting the page. The report preview will then show a broken copy of the Ubercart 404 page.