Remove unused variable

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63813 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

spec/ruby/language/constants_spec.rb

@@ -632,7 +632,6 @@ describe "Module#private_constant marked constants" do
     end
 
     it "has the defined class as the :name attribute" do
-      exception = nil
       lambda do
         ConstantVisibility::PrivConstClassChild::PRIVATE_CONSTANT_CLASS
       end.should raise_error(NameError) {|e|