# File lib/rubygems/command_manager.rb, line 136
  def find_command(cmd_name)
    possibilities = find_command_possibilities cmd_name
    if possibilities.size > 1 then
      raise "Ambiguous command #{cmd_name} matches [#{possibilities.join(', ')}]"
    elsif possibilities.size < 1 then
      raise "Unknown command #{cmd_name}"
    end

    self[possibilities.first]
  end