Created Unassigned: Html Editor Encodes & in query string when using source view [27404]

If I have a link as follows using the latest Jan 2013 build:

<a href="http://www.example.com/page.aspx?a=b&c=d">text</a>

When I switch between the source to WYSISYG and back to source view, the link becomes:

<a href="http://www.example.com/page.aspx?a=b&amp;c=d">text</a>

This is purely client side, however I am unable to track down the offending JavaScript.

Here is the HTML;

<asp:TextBox Width="100%" Height="480px" runat="server" ID="ctrlEditorPanel" TextMode="MultiLine"></asp:TextBox>
<asp:HtmlEditorExtender ID="HtmlEditorExtender1" runat="server" EnableSanitization="False"
TargetControlID="ctrlEditorPanel" OnImageUploadComplete="ImageUploadComplete"
DisplaySourceTab="true">
<Toolbar>
<asp:Undo />
<asp:Redo />
<asp:Bold />
<asp:Italic />
<asp:Underline />
<asp:StrikeThrough />
<asp:Subscript />
<asp:Superscript />
<asp:JustifyLeft />
<asp:JustifyCenter />
<asp:JustifyRight />
<asp:JustifyFull />
<asp:InsertOrderedList />
<asp:InsertUnorderedList />
<asp:CreateLink />
<asp:UnLink />
<asp:RemoveFormat />
<asp:SelectAll />
<asp:UnSelect />
<asp:Delete />
<asp:Cut />
<asp:Copy />
<asp:Paste />
<asp:BackgroundColorSelector />
<asp:ForeColorSelector />
<asp:FontNameSelector />
<asp:FontSizeSelector />
<asp:Indent />
<asp:Outdent />
<asp:InsertHorizontalRule />
<asp:HorizontalSeparator />
<asp:InsertImage />
</Toolbar>
</asp:HtmlEditorExtender>