backport #4f0f1b5 into 3-2-stable. because 1.9.3-p362 warned unused variables.

Conflicts:
	actionpack/test/controller/render_test.rb
Merge pull request #8763 from hsbt/backport-to-hide-warning

Backport 4f0f1b5 into 3-2-stable.

When running the test with warnings enabled, it fails without this change.