http: avoid possible digest mismatch error #5092

Job	Run time
prepare	5s
govulncheck	58s
binaries (darwin/amd64)	57s
binaries (darwin/arm64)	56s
binaries (linux/amd64)	2m 6s
binaries (linux/arm/v7)	1m 51s
binaries (linux/arm64)	1m 56s
binaries (linux/s390x)	1m 53s
binaries (linux/ppc64le)	1m 53s
binaries (linux/riscv64)	1m 58s
binaries (windows/amd64)	1m 56s
binaries (windows/arm64)	1m 48s
test / prepare	2m 23s
test / run (containerd, ./client ./cmd/buildctl ./worker/containerd ./solver ./frontend, integration)	11m 13s
test / run (containerd-rootless, ./client ./cmd/buildctl ./worker/containerd ./solver ./frontend, integr...	9m 18s
test / run (containerd-1.6, ./client ./cmd/buildctl ./worker/containerd ./solver ./frontend, integration)	11m 9s
test / run (containerd-snapshotter-stargz, ./client ./cmd/buildctl ./worker/containerd ./solver ./fronte...	11m 13s
test / run (oci, ./client ./cmd/buildctl ./worker/containerd ./solver ./frontend, integration)	5m 34s
test / run (oci-rootless, ./client ./cmd/buildctl ./worker/containerd ./solver ./frontend, integration)	5m 0s
test / run (oci-rootless-slirp4netns-detachnetns, ./client ./cmd/buildctl ./worker/containerd ./solver ....	5m 38s
test / run (oci-snapshotter-stargz, ./client ./cmd/buildctl ./worker/containerd ./solver ./frontend, int...	5m 4s
test / run (./..., 1, integration gateway)	4m 20s
test / run (./client, containerd, nydus, integration)	7m 28s
test / run (./client, oci, nydus, integration)	5m 3s
test / run (./..., nydus, 1, integration)	4m 41s
image	8m 36s
image (rootless)	8m 40s
release	13s
scout	0s
	2h 3m 50s

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