Log Message:
-----------
Change test -e to test -f in docs, for portability.
Modified Files:
--------------
pgsql/doc/src/sgml:
backup.sgml (r2.148 -> r2.149)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/backup.sgml?r1=2.148&r2=2.149)