Merge pull request #6388 from kennyj/fix_warning_20120519

Fix warning: possibly useless use of % in void context

activesupport/test/core_ext/string_ext_test.rb

@@ -465,7 +465,7 @@ def to_s
 
   test "Concatting with % doesn't modify a string" do
     @other_string = ["<p>", "<b>", "<h1>"]
-    "%s %s %s".html_safe % @other_string
+    _ = "%s %s %s".html_safe % @other_string
 
     assert_equal ["<p>", "<b>", "<h1>"], @other_string
   end