Merge pull request #5508 from tonistiigi/dockerfile-duplicate-args #4904

Job	Run time
prepare	1s
test / prepare	2m 8s
test / run (containerd, ./frontend/dockerfile, integration)	4m 49s
test / run (containerd, ./frontend/dockerfile, dockerfile)	10m 31s
test / run (containerd-rootless, ./frontend/dockerfile, integration)	5m 19s
test / run (containerd-rootless, ./frontend/dockerfile, dockerfile)	6m 56s
test / run (containerd-1.6, ./frontend/dockerfile, integration)	5m 37s
test / run (containerd-1.6, ./frontend/dockerfile, dockerfile)	12m 19s
test / run (containerd-1.7, ./frontend/dockerfile, integration)	5m 20s
test / run (containerd-1.7, ./frontend/dockerfile, dockerfile)	6m 53s
test / run (containerd-snapshotter-stargz, ./frontend/dockerfile, integration)	5m 11s
test / run (containerd-snapshotter-stargz, ./frontend/dockerfile, dockerfile)	10m 55s
test / run (oci, ./frontend/dockerfile, integration)	4m 48s
test / run (oci, ./frontend/dockerfile, dockerfile)	6m 3s
test / run (oci-rootless, ./frontend/dockerfile, integration)	4m 45s
test / run (oci-rootless, ./frontend/dockerfile, dockerfile)	9m 56s
test / run (oci-rootless-slirp4netns-detachnetns, ./frontend/dockerfile, integration)	4m 27s
test / run (oci-rootless-slirp4netns-detachnetns, ./frontend/dockerfile, dockerfile)	5m 44s
test / run (oci-snapshotter-stargz, ./frontend/dockerfile, integration)	4m 48s
test / run (oci-snapshotter-stargz, ./frontend/dockerfile, dockerfile)	5m 49s
image (mainline)	5m 31s
image (labs)	5m 33s
scout (master)	27s
scout (master-labs)	35s
release	0s
	2h 14m 25s

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