How to insert space in minibuffer while in completing-read ?

[Brian Adkins]

I've been using the Emacs timeclock to track my time on various
activities. When I invoke timeclock-in, I'm unable to enter a project
name containing embedded space characters (unless it's already in the
auto complete list by virtue of me manually editing the timelog file
beforehand).

I think I tracked the problem down to the completing-read function
that eventually gets invoked from timeclock-in. I put the following
snippet (from timeclock.el) in the *scratch* buffer and invoked it via
C-M-x

(completing-read "Enter string (default foo): " '("bar" "fuz") nil nil
nil nil "foo")

If I type b <space> the minibuffer will complete to bar, but I can't
then type a space. My temporary work around was to do the following:

(global-set-key (kbd "C-#") (lambda () (interactive) (insert-char ?\s
1)))

and then press C-# instead of <space> while in the minibuffer, and
that works fine :)

I suppose my question is how to unbind the <space> key from the
minibuffer-complete-word command when invoking the timeclock-in
command?