crane: Mutate does not always preserve order of env variables #1542
Description
Describe the bug
crane mutate does not always preserve order of the env variables in the json manifest. This leads to inconsistent digest of the final image.
To Reproduce
From the main branch
go run cmd/crane/main.go mutate ubuntu --platform=linux/amd64 --env=A=A --env=B=B --env=C=C --env=D=D --output=image.tar
Most the the time order is perserved but there is rare cases than:
{"architecture":"amd64","container":"8bf713004e88c9bc4d60fe0527a509636598e73e3ad1e71a9c9123c863c17c31","created":"2022-12-09T01:20:31.321639501Z","docker_version":"20.10.12","history":[{"created":"2022-12-09T01:20:30.834419054Z","created_by":"/bin/sh -c #(nop) ADD file:481dd2da6de71525248eba186feeeafcc73cc956ade0a196a4e8b0c2424e74b9 in / "},{"created":"2022-12-09T01:20:31.321639501Z","created_by":"/bin/sh -c #(nop) CMD [\"bash\"]","empty_layer":true}],"os":"linux","rootfs":{"type":"layers","diff_ids":["sha256:6515074984c6f8bb1b8a9962c8fb5f310fc85e70b04c88442a3939c026dbfad3"]},"config":{"Cmd":["bash"],"Env":["PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin","D=D","A=A","B=B","C=C"],"Image":"sha256:070606cf58d59117ddc1c48c0af233d6761addbcd4bf9e8e39fd10eef13c1bb7"}}
{"architecture":"amd64","container":"8bf713004e88c9bc4d60fe0527a509636598e73e3ad1e71a9c9123c863c17c31","created":"2022-12-09T01:20:31.321639501Z","docker_version":"20.10.12","history":[{"created":"2022-12-09T01:20:30.834419054Z","created_by":"/bin/sh -c #(nop) ADD file:481dd2da6de71525248eba186feeeafcc73cc956ade0a196a4e8b0c2424e74b9 in / "},{"created":"2022-12-09T01:20:31.321639501Z","created_by":"/bin/sh -c #(nop) CMD [\"bash\"]","empty_layer":true}],"os":"linux","rootfs":{"type":"layers","diff_ids":["sha256:6515074984c6f8bb1b8a9962c8fb5f310fc85e70b04c88442a3939c026dbfad3"]},"config":{"Cmd":["bash"],"Env":["PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin","A=A","B=B","C=C","D=D"],"Image":"sha256:070606cf58d59117ddc1c48c0af233d6761addbcd4bf9e8e39fd10eef13c1bb7"}}
Manifests have different order of env variables
Expected behavior
Mutate should always preserve order of the env variables.
Additional context
It does not work on the current main as well as 0.12.0 version.
go version go1.19.5 linux/amd64