Silence method redefined warnings when reloading thorfiles

This silences the warnings when the Thor specs are run but will still
be there when used by the end user, so it may need revisiting if we
want to eliminate warnings when using Thor as well as when testing it.

Author: pixeltrix

spec/runner_spec.rb

@@ -229,12 +229,16 @@ def when_no_thorfiles_exist
         else
           expect(File).to receive(:delete).with(path)
         end
-        silence(:stdout) { Thor::Runner.start(%w[update random]) }
+        silence_warnings do
+          silence(:stdout) { Thor::Runner.start(%w[update random]) }
+        end
       end
 
       it 'installs thor files' do
         ARGV.replace %W[install #{@location}]
-        silence(:stdout) { Thor::Runner.start }
+        silence_warnings do
+          silence(:stdout) { Thor::Runner.start }
+        end
       end
     end
   end