Update install.sh

src/install.sh

@@ -1272,6 +1272,13 @@ buildIsoPrototype() {
 
   local iso="$1"
   local dir="$2"
+
+  if ! isoinfo -d -i "$iso" > /dev/null 2>&1; then
+    info "Skipping PyCdlib prototype for non-ISO source: ${iso##*/}"
+    buildImage "$dir"
+    return
+  fi
+
   local test_dir="$STORAGE/iso-test"
   local py_iso="$TMP/pycdlib.iso"
   local gen_iso="$test_dir/genisoimage.iso"