def default_executable
    if defined?(@default_executable) and @default_executable
      result = @default_executable
    elsif @executables and @executables.size == 1
      result = Array(@executables).first
    else
      result = nil
    end
    result
  end
#
The default executable for this gem.

Deprecated: The name of the gem is assumed to be the name of the
executable now.  See Gem.bin_path.