IRB "help" command fails with an exception

[ifireball]

When trying to use the "help" command in IRB, it fails with the following exception:

NameError: undefined method `execute' for module `IRB::ExtendCommand::Help'
 from (eval):4:in `instance_method'
 from (eval):4:in `help'
 from (irb):1
 from /usr/lib/ruby/1.8/rubygems.rb:983

This problem also exists in the upstream [ruby-core:22310] but a fix was committed to the 1.9 branch in July 21, 2009, the following patch backports it to this version:
(Patch against "/usr/lib/ruby/1.8/irb/cmd/help.rb")

*** /usr/lib/ruby/1.8/irb/cmd/help.rb.orig 2011-10-19 02:53:47.000000000 +0200
--- /usr/lib/ruby/1.8/irb/cmd/help.rb 2011-10-19 03:01:54.000000000 +0200
***************
*** 9,27 ****
  #
  #

  require 'rdoc/ri/ri_driver'

  module IRB
    module ExtendCommand
! module Help
        begin
! @ri = RiDriver.new
        rescue SystemExit
        else
! def self.execute(context, *names)
            names.each do |name|
              begin
! @ri.get_info_for(name.to_s)
              rescue RiError
                puts $!.message
              end
--- 9,28 ----
  #
  #

+ require "irb/cmd/nop.rb"
  require 'rdoc/ri/ri_driver'

  module IRB
    module ExtendCommand
! class Help<Nop
        begin
! Ri = RiDriver.new
        rescue SystemExit
        else
! def execute(*names)
            names.each do |name|
              begin
! Ri.get_info_for(name.to_s)
              rescue RiError
                puts $!.message
              end

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.