prelude.rb: suppress redefinition warnings

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60952 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/irb.rb

@@ -703,7 +703,6 @@ end
 
 class Binding
   # :nodoc:
-  undef irb if method_defined?(:irb)
   def irb
     IRB.setup(eval("__FILE__"))
     workspace = IRB::WorkSpace.new(self)

prelude.rb

@@ -140,6 +140,9 @@ class Binding
     require 'irb'
     irb
   end
+
+  # suppress redefinition warning
+  alias irb irb # :nodoc:
 end
 
 module Kernel
@@ -150,4 +153,7 @@ module Kernel
     require 'pp'
     pp(*objs)
   end
+
+  # suppress redefinition warning
+  alias pp pp # :nodoc:
 end