pipestatus: handle potentially unset PIPESTATUS_VERBOSE

With `set -u`, the shell will return an error. Use `${-}` to provide an
empty default value.
8 jobs for output-to-file in 59 seconds (queued for 1 second)
Status Job ID Name Coverage
  Verify
passed #334447
docker-alpine x86_64
lint

00:00:11

passed #334448
docker-alpine ci-docker-image x86_64
test

00:00:17

 
  Build
passed #334453
docker-alpine ci-docker-image aarch64
build-aarch64

00:00:31

passed #334454
docker-alpine ci-docker-image armv7
build-armv7

00:00:34

passed #334452
docker-alpine ci-docker-image ppc64le
build-ppc64le

00:00:40

passed #334449
docker-alpine ci-docker-image s390x
build-s390x

00:00:30

passed #334451
docker-alpine ci-docker-image x86
build-x86

00:00:21

passed #334450
docker-alpine ci-docker-image x86_64
build-x86_64

00:00:20