--EXPECT--
http://www.example.com/foobar?bar.baz=blah&utm_source=google&utm_campaign=somethingelse&blat
-http://www.example.com/foobar?bar.baz=blah&utm_source=changed&utm_campaign=somethingelse
+http://www.example.com/foobar?bar.baz=blah&utm_source=changed&utm_campaign=somethingelse&blat
http://www.google.com/foobar?bar.baz=blah&utm_source=google&utm_campaign=somethingelse&blat