[1561] Unit Test icons missing when solution opens in VS 2010

Using Visual Studio 2010 Beta 2, if I have a Test Fixture C# source
document open when a solution first loads, the Unit Test icons in the
left margin do not appear.  I can run the tests from the Unit Test
Explorer, so the functionality is there, but the icons will not appear
unless I close then re-open the C# source document.