Ignore {product,system_ext} block devices in case they are symlinks

This is common on devices where maintainers have chosen not to use
real partitions because of their size being too small to be useful

build/meta/com/google/android/update-binary

@@ -175,6 +175,16 @@ exit 1
 fi
 SYSTEM_OUT="${SYSTEM_MNT}/system"
 
+# Ignore {product,system_ext} block devices in case they are symlinks
+# This is common on devices where maintainers have chosen not to use
+# real partitions because of their size being too small to be useful
+if [ -L "${SYSTEM_MNT}/product" ]; then
+PRODUCT_BLOCK=""
+fi
+if [ -L "${SYSTEM_MNT}/system_ext" ]; then
+SYSTEM_EXT_BLOCK=""
+fi
+
 if [ -n "$PRODUCT_BLOCK" ]; then
   mkdir /product || true
   if mount -o rw "$PRODUCT_BLOCK" /product; then