pgbench -f and vacuum

Currently pgbench -f (run custom script) executes vacuum against
pgbench_* tables before stating bench marking if -n (or --no-vacuum)
is not specified. If those tables do not exist, pgbench fails. To
prevent this, -n must be specified. For me this behavior seems insane
because "-f" does not necessarily suppose the existence of the
pgbench_* tables. Attached patch prevents pgbench from exiting even
if those tables do not exist. Here is the sample session:

./pgbench -f /tmp/a.sql test2
starting vacuum...ERROR: relation "pgbench_branches" does not exist
ERROR: relation "pgbench_tellers" does not exist
ERROR: relation "pgbench_history" does not exist
end.
transaction type: Custom query
scaling factor: 1
query mode: simple
number of clients: 1
number of threads: 1
number of transactions per client: 10
number of transactions actually processed: 10/10
latency average: 0.000 ms
tps = 5977.286312 (including connections establishing)
tps = 15822.784810 (excluding connections establishing)

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp