use #super from #method_missing instead of method aliasing

lib/rscons/environment.rb

@@ -246,7 +246,6 @@ module Rscons
       end
     end
 
-    alias_method :orig_method_missing, :method_missing
     def method_missing(method, *args)
       if @builders.has_key?(method.to_s)
         target, source, vars, *rest = args
@@ -261,7 +260,7 @@ module Rscons
           args: rest,
         }
       else
-        orig_method_missing(method, *args)
+        super
       end
     end
 

spec/rscons/environment_spec.rb

@@ -249,8 +249,7 @@ module Rscons
     describe "#method_missing" do
       it "calls the original method missing when the target method is not a known builder" do
         env = Environment.new
-        env.should_receive(:orig_method_missing).with(:foobar)
-        env.foobar
+        expect {env.foobar}.to raise_error /undefined method .foobar./
       end
 
       it "records the target when the target method is a known builder" do