Fix pgbench tap tests when the path contains a perl special character

When Who What
2019-03-05 15:51:42 Andrew Dunstan (adunstan) Closed in commitfest 2019-03 with status: Committed
2019-03-05 10:11:14 Raúl Marín (algunenano) New status: Ready for Committer
2019-03-01 22:28:55 Andrew Dunstan (adunstan) Added adunstan as committer
2019-02-08 13:30:51 Raúl Marín (algunenano) Posted review with messageid <154963265100.11785.6687612388485567052.pgcf@coridan.postgresql.org>
2019-02-08 13:28:29 Raúl Marín (algunenano) Added algunenano as reviewer
2019-02-08 13:28:00 Raúl Marín (algunenano) Changed authors to Fabien Coelho (calvin)
2019-02-08 13:28:00 Raúl Marín (algunenano) Changed targetversion to stable
2019-02-08 13:26:00 Raúl Marín (algunenano) Attached mail thread CAM6_UM6dGdU39PKAC24T+HD9ouy0jLN9vH6163K8QEEzr__iZw@mail.gmail.com
2019-02-08 13:26:00 Raúl Marín (algunenano) Created patch record