build_one: dedupe basename, note non-atomic cache install

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/sbo-batch-test b/sbo-batch-test
index f7ec3e9..1d68844 100755
--- a/sbo-batch-test
+++ b/sbo-batch-test
@@ -572,19 +572,22 @@ build_one() {
   if [[ "$is_target" != "1" ]]; then
     local cached; cached="$(cache_path "$cat" "$prog" "$version")"
     if [[ -n "$cached" ]]; then
+      local cb; cb="$(basename "$cached")"
       local workroot="/sbo-work"
       mkdir -p "$c$workroot"
       cp -a "$cached" "$c$workroot/"
       {
         echo "===== sbo-batch-test: $prog (from cache) ====="
-        echo "cached package: $(basename "$cached")"
+        echo "cached package: $cb"
       } >> "$logf"
-      if chroot "$c" /bin/bash -c "installpkg --terse '$workroot/$(basename "$cached")'" >>"$logf" 2>&1; then
+      if chroot "$c" /bin/bash -c "installpkg --terse '$workroot/$cb'" >>"$logf" 2>&1; then
         ST_TIME["$key"]=$(( $(date +%s) - start ))
         ST_STATUS["$key"]="CACHED"
         return 0
       fi
       # Cache install failed: fall through and build fresh.
+      # installpkg is not atomic; a partial cache install is fine here because the
+      # overlay is disposable per target. Rebuild fresh below.
       echo "cache install failed, building fresh" >> "$logf"
     fi
   fi