assignment: count_user_files() no longer creates extraneous dirs (bug…

…#4658)

Applied the fix by Samuli.Karevaara, from the bug report - the directory is checked for existence beforehand.
Previously it was created if it didn't exist, then the files within it were counted.


Author: Luke Hudson <luke@catalyst.net.nz>

mod/assignment/lib.php

@@ -1487,7 +1487,7 @@ function count_user_files($userid) {
 
         $filearea = $this->file_area_name($userid);
 
-        if ($basedir = $this->file_area($userid)) {
+        if ( is_dir($filearea) && $basedir = $this->file_area($userid)) {
             if ($files = get_directory_list($basedir)) {
                 return count($files);
             }