Setting the document creator doesn't always create a new revision

The use case is the following:

• Get a document: $xwiki.getDocument(...)
• Make a change and save it
• Set the creator reference
• Save

Result: the second save doesn't create a new revision.

This is because setCreatorReference() doesn't set the metadata dirty flag to true.
The same is true for setContentAuthorReference() and setAuthorReference().