New bug with mouse-3

[Markus Rost]

This is in recent cvs, noticed first a couple of days ago.  Clicking
down mouse-3 works usually fine, and

C-h k   click on mouse-3

pops up a help buffer as usual:
====
<mouse-3> (translated from <down-mouse-3> <mouse-3>) at that spot runs the 
command mouse-save-then-kill
   which is an interactive compiled Lisp function in `mouse'.
It is bound to <mouse-3>.
(mouse-save-then-kill CLICK)

Save text to point in kill ring; the second time, kill the text.
...
===

But after loading pcvs-defs.el, mouse-3 does not work anymore, just
beeps.  Moreover

C-h k  click on mouse-3

does not pop up a help buffer and there is a message:

<down-mouse-3> is undefined

which goes in the *Messages* buffer, but is only very shortly
displayed in the minibuffer.

This is on gnu/linux and solaris, all on X.