docker/dockerfile:1-labs is outdated (still 1.4, not 1.5)

[thaJeztah]

While writing up an example for 8bfeafa (#2799), I noticed that the docker/dockerfile:1-labs image is outdated, and still pointing to the 1.4 release of the image, not 1.5;

docker build -t foo .
[+] Building 5.1s (5/5) FINISHED
 => [internal] load .dockerignore                                                                                                                                                                              0.0s
 => => transferring context: 2B                                                                                                                                                                                0.0s
 => [internal] load build definition from Dockerfile                                                                                                                                                           0.0s
 => => transferring dockerfile: 167B                                                                                                                                                                           0.0s
 => resolve image config for docker.io/docker/dockerfile:1-labs                                                                                                                                                2.4s
 => [auth] docker/dockerfile:pull token for registry-1.docker.io                                                                                                                                               0.0s
 => docker-image://docker.io/docker/dockerfile:1-labs@sha256:639fb84e624503e26bfd33df7222eb963e5f80218d699fadd322b334d1343b6c                                                                                  0.1s
 => => resolve docker.io/docker/dockerfile:1-labs@sha256:639fb84e624503e26bfd33df7222eb963e5f80218d699fadd322b334d1343b6c                                                                                      0.0s
 => => sha256:18ee3968af166117971b0c20596722c62354c2717bbe82eb1e8db96b9c04ae9f 0B / 9.22MB                                                                                                                     0.8s
 => => extracting sha256:18ee3968af166117971b0c20596722c62354c2717bbe82eb1e8db96b9c04ae9f                                                                                                                      0.1s
dockerfile parse error on line 3: unknown flag: keep-git-dir

docker build -t foo .
[+] Building 15.9s (10/10) FINISHED
 => [internal] load .dockerignore                                                                                                                                                                              0.0s
 => => transferring context: 2B                                                                                                                                                                                0.0s
 => [internal] load build definition from Dockerfile                                                                                                                                                           0.0s
 => => transferring dockerfile: 173B                                                                                                                                                                           0.0s
 => resolve image config for docker.io/docker/dockerfile:1.5.0-labs                                                                                                                                            1.6s
 => docker-image://docker.io/docker/dockerfile:1.5.0-labs@sha256:c2c8f7e206e5b98ce31f68ca5507bb5f21a4acece6527097508a6f24d94e8fec                                                                              0.1s
 => => resolve docker.io/docker/dockerfile:1.5.0-labs@sha256:c2c8f7e206e5b98ce31f68ca5507bb5f21a4acece6527097508a6f24d94e8fec                                                                                  0.0s
 => => sha256:7bf2f772a794cc7221765141db0c1c78758bf9eb1d76c17b9f9984f072b89a7f 10.82MB / 10.82MB                                                                                                              11.9s
 => => extracting sha256:7bf2f772a794cc7221765141db0c1c78758bf9eb1d76c17b9f9984f072b89a7f                                                                                                                      0.1s
 => [internal] load metadata for docker.io/library/alpine:latest                                                                                                                                               1.8s
 => [auth] library/alpine:pull token for registry-1.docker.io                                                                                                                                                  0.0s
 => git://github.com/moby/buildkit.git#v0.10.1                                                                                                                                                                 6.0s
 => CACHED [1/2] FROM docker.io/library/alpine@sha256:f271e74b17ced29b915d351685fd4644785c6d1559dd1f2d4189a5e851ef753a                                                                                         0.0s
 => => resolve docker.io/library/alpine@sha256:f271e74b17ced29b915d351685fd4644785c6d1559dd1f2d4189a5e851ef753a                                                                                                0.0s
 => [2/2] ADD --keep-git-dir=true https://github.com/moby/buildkit.git#v0.10.1 /buildkit                                                                                                                       0.7s
 => exporting to image                                                                                                                                                                                         1.8s
 => => exporting layers                                                                                                                                                                                        1.3s
 => => exporting manifest sha256:fd0d80903d17464e7d70a450cc8509a2d0069dd6e44b423d6a276a47123f6633                                                                                                              0.0s
 => => exporting config sha256:9d4c8d65f4eeddfaeda6126fd0a2e5ed01ad9d0e56ab0821ca05bb1f39eb9fd0                                                                                                                0.0s
 => => naming to docker.io/library/foo:latest                                                                                                                                                                  0.0s
 => => unpacking to docker.io/library/foo:latest                                                                                                                                                               0.5s

[thaJeztah]

Actually, looks like the same is true for the stable dockerfile;

[crazy-max]

Should be good now