Diary font-lock problem

[Stephen Berman]

I would like to have diary entries of the form

Thu, Apr 5, 2007 Today's entry

in which the string "Thu, Apr 5, 2007" has diary face.  This
fontification is not provided by the default diary setup, but I had
hoped and expected to get it by customizing diary-date-forms
appropriately.  However, after making what I think is the necessary
customization, I still don't get the fontification I want.  I can
reproduce the problem with emacs -Q:

1. Let ~/.emacs consist only of this sexp:

txtY3qt_ToLJb.txt
Description: ~/.emacs

2. emacs -Q

3. M-x calendar

4. In the calendar type `s' to show the whole diary, then in the diary
buffer type the above entry.  Only "Thu," has diary face.

If I eval diary-font-lock-keywords I get this:

txtbXEEu4ifAi.txt
Description: diary-font-lock-keywords

The sexp immediately preceding `...' contains the result of the
customization I made above, and the regexp it contains is
string-match'd by the above diary entry string:

txtXwj1rl2DZe.txt
Description: string-match

Therefore, I assume my customization is what I want and I would expect
the entire date string to have diary face.  Should I be doing
something else to get the fontification I want (and if so, what) or is
there a bug here?

Steve Berman