nice(3) is supposed to return the new nice value. nice(3) in Advanced Server does not.
Do we really want that fix for 2.1AS though? It was breaking VMWare, made bogus errors in XFree86 logs etc.
Fixed in glibc-2.2.4-27.1.
the LSB added language to allow both behaviors, so we can make nice() do the old thing for AS 2.1.