git: allow cloning commit shas not referenced by branch/tag #5228

Job	Run time
govulncheck	59s
prepare	7s
binaries (darwin/amd64)	58s
binaries (darwin/arm64)	1m 1s
binaries (linux/amd64)	1m 53s
binaries (linux/arm/v7)	2m 3s
binaries (linux/arm64)	2m 7s
binaries (linux/s390x)	1m 59s
binaries (linux/ppc64le)	1m 53s
binaries (linux/riscv64)	2m 16s
binaries (windows/amd64)	1m 50s
binaries (windows/arm64)	1m 35s
test / prepare	1m 57s
test / run (containerd, ./client ./cmd/buildctl ./worker/containerd ./solver ./frontend, integration)	8m 24s
test / run (containerd-rootless, ./client ./cmd/buildctl ./worker/containerd ./solver ./frontend, integr...	9m 46s
test / run (containerd-1.6, ./client ./cmd/buildctl ./worker/containerd ./solver ./frontend, integration)	8m 5s
test / run (containerd-snapshotter-stargz, ./client ./cmd/buildctl ./worker/containerd ./solver ./fronte...	9m 6s
test / run (oci, ./client ./cmd/buildctl ./worker/containerd ./solver ./frontend, integration)	7m 38s
test / run (oci-rootless, ./client ./cmd/buildctl ./worker/containerd ./solver ./frontend, integration)	7m 33s
test / run (oci-rootless-slirp4netns-detachnetns, ./client ./cmd/buildctl ./worker/containerd ./solver ....	7m 33s
test / run (oci-snapshotter-stargz, ./client ./cmd/buildctl ./worker/containerd ./solver ./frontend, int...	6m 13s
test / run (./..., 1, integration gateway)	4m 39s
test / run (./client, containerd, nydus, integration)	8m 7s
test / run (./client, oci, nydus, integration)	7m 18s
test / run (./..., nydus, 1, integration)	8m 44s
image	9m 21s
image (rootless)	8m 50s
release	6s
scout	0s
	2h 12m 1s

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