Is there any way to stop the default behavior of clearing out query string variables from the URL when using a PageReference with redirect set to false?

I have a page that renders different links depending on a "country" variable.  The Australia URL looks something like:

http://mydomain/tools/mytool?country=au

There is a form on that page, and on submit, you are redirected to the "mytool2" page which uses the same controller.  Since the PageReference redirect is set to false, this is not a client-side redirect.  However, for whatever reason, when the redirect happens, my browser's URL suddenly has the country query string truncated and becomes http://mydomain/tools/mytool.

While this doesn't affect any functionality, the problem is that this could confuse my Australian customers if they ever try and bookmark the post-submitted page URL that is missing the correct query string.  And if they hit the site without ?country=au, they will end up with incorrect links for their locale.

Why is Salesforce deleting my query string at all?  Is there any way to avoid this from happening?

Here is a simplified version of what the code looks like:

"mytool" (Page 1 with form)

<apex:page showheader="false" sidebar="false" controller="myController">
<apex:form >
<apex:pageblock title="Choose from the following options"
			mode="maindetail">
  **Various form input fields**
  <apex:commandbutton value="Submit" action="{!Submit}" />
</apex:pageblock>
</apex:page>

"mytool2" (Page 2)

<apex:page sidebar="false" standardstylesheets="false" cache="false"
	showHeader="false" controller="myController">

**Various outpanels displayed depending on what was selected from the first page**

</apex:page>

"myController" (Controller used by both pages)

public with sharing class myController{
  public PageReference submit(){
    return Page.mytool2;
  }
}