Fix PTS continuity in sequences of copied streams. #9708

Job	Run time
build_details	2s
pre-commit	3m 7s
build_js	1m 24s
lezer_parse	51s
tree_sitter_parse	51s
run_tests (@citest)	11m 47s
build_no_depopts	5m 42s
run_tests (@doctest)	8m 22s
update_doc	0s
run_tests (@mediatest)	13m 38s
build_opam (4.14.x)	4m 53s
build_posix (debian_trixie, amd64)	16m 32s
build_opam (5.0.x)	4m 57s
build_win32 (x64)	11m 8s
build_posix (debian_bookworm, amd64)	14m 34s
build_posix (ubuntu_jammy, amd64)	15m 40s
build_posix (ubuntu_lunar, amd64)	14m 34s
build_posix (alpine, amd64)	11m 2s
fetch_s3_artifacts	24s
build_docker (amd64)	2m 17s
build_docker_alpine (amd64)	56s
update_release	0s
build_docker_alpine_minimal (amd64)	1m 3s
build_docker_minimal (amd64)	4m 13s
build_docker_release	0s
build_docker_release-minimal	0s
	2h 27m 57s

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