fix(shell): remove test harness pipe hazards (#1106)

Co-authored-by: f10-coder <[email protected]>

packages/mosaic/framework/tools/quality/scripts/test-upgrade-durable-snapshot.sh

@@ -176,8 +176,12 @@ run_snap() {
 
 # Resolve the single pre-update-* snapshot dir under a state dir (newest if many).
 snap_dir() {
-  find "$1/mosaic/backups" -maxdepth 1 -type d -name 'pre-update-*' 2>/dev/null \
-    | LC_ALL=C sort -r | head -1
+  local -a snapshots=()
+  mapfile -t snapshots < <(
+    find "$1/mosaic/backups" -maxdepth 1 -type d -name 'pre-update-*' 2>/dev/null \
+      | LC_ALL=C sort -r
+  )
+  printf '%s\n' "${snapshots[0]:-}"
 }
 
 echo "── Part 1/2/3: durable snapshot scope, perms, no-leak ──────────────────"