The only things which I know about to prevent a release now, is that the
"Help" -> "Development News" menu will try to open the yet not existning
http://www.gnu.org/software/xboard/whats_new/portal.html, while the
About text mentions http://www.gnu.org/software/xboard/whats_new.html
I don't think that has to stop the release, as it is a website problem,
and not an XBoard problem. The portal page should be created, to
automatically redirect to the page we think is most appropriate at the
time. (This should currently be the 4.6.0 news page, I think.) The
whats_new page also exists.