bug 1505652: [taskgraph] Download debian packages from latest run of package task; r=dustin

If a packaging task ended up being retried for any reason, the downstream
docker tasks that depended on them would fail, since they were hard-coding the
artifacts from the initial run.

Differential Revision: https://phabricator.services.mozilla.com/D7364

taskcluster/docker/debian-base/setup_packages.sh

@@ -1,5 +1,5 @@
 #!/bin/sh
 
 for task in "$@"; do
-  echo "deb [trusted=yes] https://queue.taskcluster.net/v1/task/$task/runs/0/artifacts/public/build/ debian/" > "/etc/apt/sources.list.d/99$task.list"
+  echo "deb [trusted=yes] https://queue.taskcluster.net/v1/task/$task/artifacts/public/build/ debian/" > "/etc/apt/sources.list.d/99$task.list"
 done

taskcluster/taskgraph/transforms/job/debian_package.py

@@ -170,7 +170,7 @@ def docker_worker_debian_package(config, job, taskdesc):
         'apt-get install -yyq apt-transport-https ca-certificates && '
         'for task in $PACKAGES; do '
         '  echo "deb [trusted=yes] https://queue.taskcluster.net/v1/task'
-        '/$task/runs/0/artifacts/public/build/ debian/" '
+        '/$task/artifacts/public/build/ debian/" '
         '>> /etc/apt/sources.list; '
         'done && '
         # Install the base utilities required to build debian packages.