Reproduction

1. Have a book with two versions
2. Create a new unversioned page
3. Switch between versions with the selector

Result

If you use the following snippet, you'll see that the saved selected version in the user session has been changed wrongly by including the query parameters

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

This is an example that I got:

TopBook.WebHome=masterw:TopBook.v1?unVersion=TopBook.v2?unVersion=TopBook.v1

Also, the URL cumulates the "unVersion" query parameters.

Expectation

The version reference shouldn't have query parameters and the URL shouldn't have many of them (maybe using the query parameter is useless since BVERSION-94 modifications)