protection against accidental massive pastes into the command line

[jidanni]

Maybe there should be a limit, MAX_INTERACTIVE_COMMAND_LENGTH on how
much can be fed into one bash command line, any more and bash should
beep and reject the whole command.

Otherwise an innocent middle click, or SHIFT INSERT slip of the fingers
could paste an entire book out of the clipboard, into the command line,
which would then cause bash to try to execute every line.