Confluence preview generator corrupts HTML files with Microsoft VML content

Summary

Some HTML pages prepared by Microsoft Tools using VML became corrupted after being upload as an attachment into Confluence

Steps to Reproduce

1. Create GPO Report from an MS 2012 Server
2. Upload the resulted html file gpo-ok.html to Confluence
3. Download the attachment and try to open with a browser - result gpo-damaged.html

Expected Results

The attachment file downloaded in the same state as it was uploaded

Actual Results

The attachment content is changed

Workaround

Upload the report in txt and then change the file extension back to html. Or print into PDF.

Notes

In Confluence 5.10-beta2 the issue is solved.