fix: [sftp] ensure that cache won't be used with a different version of the function

sftp/lib/common

@@ -2,7 +2,7 @@
 
 
 make_build_script() {
-    local users_def="$1" cache_file="$CACHEDIR/$FUNCNAME.cache.$(p0 "$@" | md5_compat)"
+    local users_def="$1" cache_file="$CACHEDIR/$FUNCNAME.cache.$(p0 "$@" "$(declare -f "$FUNCNAME")" | md5_compat)"
     if [ -e "$cache_file" ]; then
         #debug "$FUNCNAME: STATIC cache hit"
         cat "$cache_file" &&