bug#2944: 23.0.91; vc-dir confusing at startup

[Richard M Stallman]

    The problem with not showing something in VC buffer is a common one for
    asynchronous VC commands (diff, log).  The solution we have in emacs-23
    for that is to add [Working...] on the modeline while such command is in
    progress.  Was that not obvious enough?  Does the face for that message
    need to stand out a bit more?

It will be clear enough to people who look for it, I suppose,
but I did not notice it at all.  I think it is desirable to put something
temporarily in the buffer saying "the data is not really here yet".