Fix append operator. (#4152) #11584

Job	Run time
build_js	2m 13s
build_js	2m 13s
build_details	4s
build_details	4s
build_opam (4.14.x)	9m 13s
build_opam (4.14.x)	9m 13s
build_opam (5.2.x)	5m 25s
build_opam (5.2.x)	5m 25s
tree_sitter_parse	46s
tree_sitter_parse	46s
lezer_parse	53s
lezer_parse	53s
build_no_depopts	5m 48s
build_no_depopts	5m 48s
build_win32 (x64)	17m 30s
build_win32 (x64)	17m 30s
run_tests (@citest)	18m 38s
run_tests (@citest)	12m 10s
build_posix (debian_trixie, amd64)	13m 11s
build_posix (debian_trixie, amd64)	13m 11s
run_tests (@doctest)	7m 33s
run_tests (@doctest)	7m 33s
update_doc	11m 32s
update_doc	11m 32s
build_posix (debian_bookworm, amd64)	14m 37s
build_posix (debian_bookworm, amd64)	14m 37s
run_tests (@mediatest)	12m 17s
run_tests (@mediatest)	12m 17s
build_posix (ubuntu_oracular, amd64)	15m 39s
build_posix (ubuntu_oracular, amd64)	15m 39s
build_posix (ubuntu_noble, amd64)	13m 38s
build_posix (ubuntu_noble, amd64)	13m 38s
build_posix (alpine, amd64)	12m 4s
build_posix (alpine, amd64)	12m 4s
fetch_s3_artifacts	21s
fetch_s3_artifacts	21s
build_docker (amd64)	2m 5s
build_docker (amd64)	2m 5s
build_docker_alpine	0s
build_docker_alpine	0s
update_release	0s
update_release	0s
build_docker_minimal	0s
build_docker_minimal	0s
build_docker_alpine_minimal	0s
build_docker_alpine_minimal	0s
build_docker_release	0s
build_docker_release	0s
build_docker_release-minimal	0s
build_docker_release-minimal	0s
	5h 20m 26s

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