XWikiAttachment#getContentInputStream() returns the content for the latest version if the content is not already loaded

If you have an attachment that has two versions, 1.1 and 1.2, where 1.1 corresponds to document version X and 1.2 to document version Y, then calling getContentInputStream() on the 1.1 version obtained from X will return the content from version 1.2.

The reasons is this:

• we store only the latest version of an attachment in xwikiattachment_content (where the content is identified by the file name and the document reference)
• the rest of the versions are stored in xwikiattachment_archive
• if the attachment content is not loaded or set then getContentInputStream() always loads the content from xwikiattachment_content (so the latest stored version).