revert: fix incorrect variable name

7 jobs for master in 2 minutes and 2 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #24437
docker-in-docker
build_artful_amd64

00:01:00

passed #24435
docker-in-docker
build_buster_amd64

00:01:12

passed #24432
docker-in-docker
build_jessie_amd64

00:00:59

passed #24434
docker-in-docker
build_sid_amd64

00:01:13

passed #24433
docker-in-docker
build_stretch_amd64

00:01:06

passed #24436
docker-in-docker
build_zesty_amd64

00:02:01

passed #24438
docker-in-docker
test_jessie_amd64

00:00:42