Removed unused mu_pp method

tool/lib/test/unit/assertions.rb

@@ -88,17 +88,6 @@ module Test
         tempfile_b.close! if tempfile_b
       end
 
-      ##
-      # This returns a human-readable version of +obj+. By default
-      # #inspect is called. You can override this to use #pretty_print
-      # if you want.
-
-      def mu_pp obj
-        s = obj.inspect
-        s = s.encode Encoding.default_external if defined? Encoding
-        s
-      end
-
       ##
       # This returns a diff-able human-readable version of +obj+. This
       # differs from the regular mu_pp because it expands escaped