Site Import causes users to show as Anonymous in metadata

When using the Site Importer tool in the latest Confluence OnDemand release (5.3-OD-7), all content ownership is set to 'Anonymous'. This can be reproduced when importing a full backup from a standalone Confluence (tested with 5.2.5). Looking into the database, we can see that "creator" and "lastmodifier" are null for any imported page.

Steps to reproduce

1. Create a backup from a Confluence v.5.2.5 (or use the backup attached)
2. Import that backup via Import Site menu in a Confluence 5.3-OD-7

Expected results

Page/Blog creators or modifiers are correctly displayed

Actual results

Page/Blog creators or modifiers are shown as anonymous