Reproduction

Note: you can import the attached book. to avoid creating the pages yourself

1. Create a book with:
   1. version 1
   2. version 2, preceding version is version 1
2. Create pages for this book
   1. First page with content for the 2 versions
   2. Second page with content for the 2 versions
   3. Third page with only version for version 1 (it will need to select version 1 before creating the page)
3. Go to the first page and select version 2
4. Go to the second page
   1. The version 2 is selected in the dropdown menu => expected result
   2. The content from version 2 is displayed => expected result
5. Go to the third page
   1. The version 1 is selected in the dropdown menu => unexpected result, it should remain on version 2
   2. The content from version 1 is displayed =>  expected result
   3. If you use the following snippet, you'll see that the saved selected version in the user session has been changed to version 1 

      {{velocity}}
      |=Att name|=Att value
      #foreach($att in $request.getSession().getAttributeNames())
        |$att|$request.getSession().getAttribute($att)
      #end
      {{/velocity}}

1. Go back to the first page
   1. The version 1 is selected in the dropdown menu => unexpected result, it should remained on version 2
   2. The content from version 1 is displayed =>  unexpected result, it should have displayed version 2