The cluster can lead to an inconsistent state of the cached XWikiDocument instance

When receiving a document related event, the XWikiDocument is most of the time gathered from the cache, and the original document is modified to be consistent from listeners point of view.

The problem is that what is good for listeners is also wrong for the cache and a document with a bad original document (in the cache the original document should be always be equals to the document in terms of data) is left in the cache.