The development docs at
http://developer.postgresql.org/docs/postgres/index.html
are at least a week behind CVS tip. The build log
http://developer.postgresql.org/docs/postgres/buildlog.html
seems current, but something's failing to move the rebuilt
files into place(?)
FWIW, the breakage seems to have occurred between 7-11 and 7-19.
regards, tom lane