restoring wal archive and pg_xlog dir

When reading the docs on recovery.conf, I noticed this:

WAL segments that cannot be found in the archive will be sought in pg_xlog/;
this allows use of recent un-archived segments. However segments that are
available from the archive will be used in preference to files in pg_xlog/. The
system will not overwrite the existing contents of pg_xlog/ when retrieving
archived files.

If the system will use the files in the archive in preference to the ones in
pg_xlog, how can this actually happen if it will not overwrite the contents of
pg_xlog?

I also noticed that if there is not at least one wal archive available in
the archive or the pg_xlog dir, the restore errors out and exits. So the
base backup is really not complete without at least one wal archive
following it. Is this by design?

--
Jeff Frost, Owner <jeff(at)frostconsultingllc(dot)com>
Frost Consulting, LLC http://www.frostconsultingllc.com/
Phone: 650-780-7908 FAX: 650-649-1954