Cannot find attachment data intermittently in OnDemand

Steps to reproduce

1. Make sure you have cloud conversions set up (this is making its way to prod soon)
   1. To set this up manually you need an OD instance with: Document Conversion Library + Confluence Document Conversion Library + Cloud Conversions Enabler
2. Create a page with 100 attachments - even small .txt files will do
3. Save the page
4. Confluence starts sending the files over to DocTape
5. Some files fail with the following exception coming from core

2015-01-09 12:23:08,658 ERROR [pool-1321-thread-1] [atlassian.confluence.pages.DefaultAttachmentManager] getAttachmentData Could not find data for attachment: Attachment: SHINFUJI_1020_19-24OCT1014_FUJI-TOKYO copy 3.docx v.1 (2523901) sysadmin - com.atlassian.confluence.pages.persistence.dao.filesystem.AttachmentDataFileSystemException: No such file for Attachment: SHINFUJI_1020_19-24OCT1014_FUJI-TOKYO copy 3.docx v.1 (2523901) sysadmin

Here's what's going on in the plugin:

• The plugin is listening for AttachmentCreateEvent
• Core triggers the event after the file is written to disk
• The plugin adds the attachment to a queue to be sent to the doctape service
• An executor picks up the work and attempts to get an InputStream to the file via AttachmentManager#getAttachmentData(Attachment)
• Core logs the above error and returns us a null

I suspect it might be related to http://bugs.java.com/bugdatabase/view_bug.do?bug_id=5003595