refactor: dedupe findmnt invocation in safe_cleanup_work_dir

The catch-all mount-cleanup block called findmnt twice (once as an
existence guard, once in the pipe). Consolidate to a single call
captured to a local, guard with -n test. No behavior change — same
mounts, same order, same lazy-unmount.

Left the explicit known-mount loop alone; it's a faster path for the
deterministic mkarchiso bind mounts, with findmnt as the catch-all
for anything else. Not parallel strategies, just fast path + fallback.

1 files changed, 8 insertions, 4 deletions

diff --git a/build.sh b/build.sh
index c494ef7..6144932 100755
--- a/build.sh
+++ b/build.sh
@@ -48,11 +48,15 @@ safe_cleanup_work_dir() {
             fi
         done
 
-        # Also catch any other mounts we might have missed
-        if findmnt --list -o TARGET 2>/dev/null | grep -q "$airootfs"; then
-            findmnt --list -o TARGET 2>/dev/null | grep "$airootfs" | sort -r | while read -r mp; do
+        # Catch any other mounts under airootfs (bind mounts not in the
+        # explicit list above). Deepest-first via reverse sort.
+        local leftover
+        leftover=$(findmnt --list --noheadings -o TARGET 2>/dev/null \
+                       | grep "$airootfs" | sort -r)
+        if [[ -n "$leftover" ]]; then
+            while IFS= read -r mp; do
                 umount -l "$mp" 2>/dev/null || true
-            done
+            done <<< "$leftover"
         fi
 
         # Small delay to let lazy unmounts complete