Fix: utils.sh: handle SIGPIPE

perl prove closes its child pipes before giving it a chance to execute
the signal trap handler. This means the child will not be able to
complete execution of the trap handler if that handler writes to stdout
or stderr.

Work-around this situation by redirecting stdin, stdout, and stderr
to /dev/null if a SIGPIPE is caught.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>