fix: correct sed delimiter in GH_REPO_URL extraction (#63)

[kurok]

Summary

Fixes #63.

buildReusableUserData()'s per-boot registerScript extracted GH_REPO_URL with sed using # as the delimiter, while the GH_TOKEN and GH_LABEL extraction lines directly above it correctly use /. Because the sed pattern ends in the end-of-line anchor $ immediately followed by the # delimiter, and the whole sed argument sits inside a double-quoted shell string, bash expands $# (the special "number of positional arguments" parameter, always 0 for this script) before sed ever sees it. That corrupts the sed script into s#^GH_REPO_URL='\(.*\)'0\1#p, which errors with unterminated 's' command.

Since this is a plain GH_REPO_URL=$(...) assignment under set -euo pipefail (no || true guard), the sed failure aborts the whole registerScript at the configuring phone-home step — before config.sh is ever invoked. This is a 100% reproducible failure for every reuse: stop warm-pool launch.

Fix

Swap the delimiter to ,, which isn't a bash special-parameter suffix when preceded by $:

-'GH_REPO_URL=$(printf \'%s\\n\' "$UD" | sed -n "s#^GH_REPO_URL=\'\\(.*\\)\'$#\\1#p" | head -n1)',
+'GH_REPO_URL=$(printf \'%s\\n\' "$UD" | sed -n "s,^GH_REPO_URL=\'\\(.*\\)\'$,\\1,p" | head -n1)',

Verified against both BSD sed (macOS) and GNU sed semantics — this mirrors the exact root cause and fix from the issue writeup.

Test plan

• Added a regression test in tests/warmpool.test.js that extracts the actual GH_REPO_URL=$(... sed ...) line out of the real generated user-data (not a reimplementation) and executes it in bash with a controlled fake IMDS user-data value.
• Verified the new test fails against the old #-delimiter line (sed: unescaped newline inside substitute pattern, command exits non-zero under set -e).
• Verified the new test passes against the fix (extracts https://github.com/foo/bar correctly).
• Full suite: npm test — 227/227 passing (226 pre-existing + 1 new).
• npm run lint — clean.
• npm run package — rebuilt dist/index.js; confirmed the rebuild is deterministic (byte-identical across two consecutive runs) and the diff is scoped to the single fixed line.