Good catch.

Unfortunately trying to fix it got really complicated really fast. Ruby's Readline module doesn't understand that escaped spaces (`'\ '`) aren't a break between arguments, so when it's given `add a\ text` to complete it assumes we are completing the word `text` and not the phrase `a\ text`. We have access to enough information to figure out that this is happening, and return `['a\ text\ file', 'a\ text\ document']` or `['\ file', '\ document']`, but in either case there are circumstances where that's the wrong thing to do, and the Ruby bindings don't give us enough information to figure out which would be correct for the current situation.

What we really need to do is tell Readline how to determine if a character is escaped. Conveniently, we can do this using [`rl_char_is_quoted_p`](http://cnswww.cns.cwru.edu/php/chet/readline/readline.html#IDX364). Inconveniently, the Ruby bindings don't expose this method.