tools: {export,install}.sh: fix quoting issues

export.sh

@@ -111,16 +111,19 @@ __main() {
     then
         path_prefix=${PATH%%${old_path}}
         # shellcheck disable=SC2169,SC2039  # unreachable with 'dash'
-        paths="${path_prefix//:/ }"
-        if [ -n "${paths}" ]; then
+        if [ -n "${path_prefix}" ]; then
             __verbose "Added the following directories to PATH:"
         else
             __verbose "All paths are already set."
         fi
-        for path_entry in ${paths}
+        old_ifs="$IFS"
+        IFS=":"
+        for path_entry in ${path_prefix}
         do
             __verbose "  ${path_entry}"
         done
+        IFS="$old_ifs"
+        unset old_ifs
     else
         __verbose "Updated PATH variable:"
         __verbose "  ${PATH}"