`! docker buildx inspect | grep -q linux/arm64` under `set -o pipefail` fails
when grep exits on its first match before buildx has finished writing: buildx
dies of SIGPIPE, the pipeline reports 141, and the script tells the operator to
register emulation that is already registered. It refused to publish twice in a
row that way, with arm64 present each time — and the same race is why it ever
worked. Matching against the captured output has no pipe to break.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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