Create multiple pages at same time returns a 'Page not Found' error

If you are creating multiple pages at your browser and after making all the changes you decide to save one after the other some pages will get created and other will not.

Steps to reproduce:

1. Set up a Confluence 5.6.6.
2. Open two (or more) tabs with Confluence.
3. Press the 'Create' button on all Confluence pages.
4. Start working on the pages.
5. Save those pages one after the other.
6. Some pages will get created and others will not. The only error in the logs will be a warning:

   2015-04-22 15:58:00,441 WARN [http-bio-8090-exec-9] [confluence.content.service.DefaultDraftService] removeDraft Attempt to remove draft with 0 draftId from unfound content with id: 0
    -- referer: http://confluence:8090/pages/createpage.action?spaceKey=OS | url: /pages/docreatepage.action | userName: admin | action: docreatepage
   

Resolution:

Upgrade to Confluence 5.7.1 where we couldn't reproduce this error.