Fix content used for preview not updated after update in Nuxeo

reproduction step:

• create a doc from Nuxeo Web UI
• Preview it from the annotation tab 
• Update the content of the created doc, with a new file (there is a replace icon below the file preview on the main document tab)
• Go back to annotation tab

Prbm: the previewed content is still the first one set on the doc, not the new. Refresh etc won't change anything.