That version's obsolete anyway, we've changed the tree sortkey representation entirely.
Yesterday I learned, to my disgust, that our nightly tarballs have been failing for about two months. I may have time later today to look into this, but until then your best bet is to use anonymous CVS to grab the sources. Try this:
nsadmin:/web$ cvs -d:pserver:anonymous@openacs.org:/cvsroot login
(Logging in to anonymous@openacs.org) CVS Password: [just hit RETURN]
nsadmin:/web$ cvs -z3 -d:pserver:anonymous@openacs.org:/cvsroot checkout acs-core
