When the deploy batch has more than 20 commits, the `git log ... | head -20`
pipeline closes the pipe after 20 lines. git log gets SIGPIPE (exit 141),
which `set -o pipefail` propagates, and `set -e` then exits the script
silently — no prompt shown, no error message.
Only bites for release-sized batches (>20 commits). First seen on the
v1.3.0 prod deploy: 20 commits displayed, then the script returned to
the shell without prompting. dev deploys never hit this because they
typically only have 1-3 commits ahead.
Fix: tell git to limit its own output via `-n 20`. Same display, no
broken pipe. Also swap the count-by-wc-l for `git rev-list --count`
which is more idiomatic and avoids any further pipe shenanigans.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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