Why did you post this here? Sounds more like a bug to me. (though, not much of one)
Maybe it shouldn\'t save a failed command to the history, but it is a history of what you did, and you
did do that command.

Regardless, you can just press down to clear. I\'ve made the current version\'s chat history a bit smarter, but I think even the release client can do that.
Edited to add:Why are you leaving a space anywhy? Just clear the whole thing... I don\'t quite see how this could come up.