gitness: Builds occasionally stuck in the "Building" state with Docker 1.12

In the continuation of https://gitter.im/drone/drone?at=5803905e891a53016314d30d

uname -a

Linux drone 4.4.0-31-generic #50-Ubuntu SMP Wed Jul 13 00:07:12 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

docker version

Client:
 Version:      1.12.2
 API version:  1.24
 Go version:   go1.6.3
 Git commit:   bb80604
 Built:        Tue Oct 11 18:29:41 2016
 OS/Arch:      linux/amd64

Server:
 Version:      1.12.2
 API version:  1.24
 Go version:   go1.6.3
 Git commit:   bb80604
 Built:        Tue Oct 11 18:29:41 2016
 OS/Arch:      linux/amd64

commands to start drone server:

docker network create drone-server-net

docker run -d \
    --name=drone-server \
    -e DRONE_SECRET=$DRONE_SECRET \
    -e DRONE_GITHUB=true \
    -e DRONE_GITHUB_CLIENT=$GITHUB_CLIENT \
    -e DRONE_GITHUB_SECRET=$GITHUB_SECRET \
    -e DRONE_ORGS=$GITHUB_ORG \
    -e DRONE_OPEN=true \
    -e DRONE_ADMIN=$GITHUB_ADMIN_USERS \
    -v drone-data:/var/lib/drone \
    --net=drone-server-net \
    -p 80:8000 \
    drone/drone:0.5 server

docker run -d \
    -e DRONE_SECRET=$DRONE_SECRET \
    -e DRONE_SERVER=ws://drone-server:8000/ws/broker \
    -e DRONE_TIMEOUT=15m \
    -e DOCKER_MAX_PROCS=4 \
    -v /var/run/docker.sock:/var/run/docker.sock \
    --net=drone-server-net \
    drone/drone:0.5 agent

YAML:

pipeline:

  build:
    image: node:6.8
    commands:
      - npm i gulp webpack karma --color=always -q

matrix:
  include:
    - axis: 1
    - axis: 2
    - axis: 3
    - axis: 4

When all worker container are exited, some builds occasionally are stuck in “orange” state:

---

---

---

And containers are not removed, ambassador exit code is 137:

docker ps -a

CONTAINER ID        IMAGE                COMMAND                  CREATED             STATUS                            PORTS                  NAMES
740c7d3519af        node:6.8             "/bin/sh -c 'echo $DR"   3 minutes ago       Exited (0) About a minute ago                            drone_dUpqOVZnNW4_1
d5a19a6bed0f        plugins/git:latest   "/bin/drone-git"         3 minutes ago       Exited (0) 3 minutes ago                                 drone_dUpqOVZnNW4_0
931454065d90        busybox:latest       "/bin/sleep 86400"       3 minutes ago       Exited (137) About a minute ago                          drone_ambassador_aa49ZRmHlfA
f8e6526d9611        drone/drone:0.5      "/drone agent"           17 minutes ago      Up 17 minutes                     8000/tcp               drunk_ritchie
2d36a428e71a        drone/drone:0.5      "/drone server"          17 minutes ago      Up 17 minutes                     0.0.0.0:80->8000/tcp   drone-server

The issue doesn’t not occur without --color=always (i.e. with no console colors).