SafeBuffer#gsub test still failing for $1

* ensured the block is passed, refactor test so can't be mislead if block never called

activesupport/lib/active_support/core_ext/string/output_safety.rb

@@ -129,8 +129,8 @@ def #{unsafe_method}!(*args)
     #
     # If you really need the magic matching variables after the gsub call
     # you will need to convert SafeBuffer to a String first
-    def gsub(*args)
-      to_str.gsub(*args)
+    def gsub(*args, &block)
+      to_str.gsub(*args, &block)
     end
   end
 end

activesupport/test/safe_buffer_test.rb

@@ -54,7 +54,9 @@ def setup
   test "Should set magic match variables within block passed to gsub" do
     'burn'[/(matches)/]
     @buffer << 'swan'
-    @buffer.gsub(/(swan)/) { assert_equal 'swan', $1 }
+    result = nil
+    @buffer.gsub(/(swan)/) { result = $1 }
+    assert_equal 'swan', result, "dang it, still not working"
   end
 
   test "Should not expect magic match variables after gsub call" do