MDL-16061 Revert incorrect fix for "Remove 'username' from the $moodleattributes array"

The fix is wrong, as it breaks auth_db_sync_users.php and
auth_ldap_sync_users.php at least. No new users are added to Moodle, as the
username is missing from the new user info record.

The fix needs to go into update_user_record() in lib/moodlelib.php to make it
skip the 'username' key, as we really need get_userinfo() to return the
username as part of the user info array.

auth/cas/auth.php

@@ -495,6 +495,7 @@ if ( !is_object($PHPCAS_CLIENT) ) {
                 }
             }
         }
+        $moodleattributes['username'] = $this->config->user_attribute;
         return $moodleattributes;
     }
     /**
@@ -1122,4 +1123,4 @@ if (!empty($this->config->attrcreators)) {
         return $text;
     }
 }
-?>
+?>

auth/db/auth.php

@@ -135,6 +135,7 @@ class auth_plugin_db extends auth_plugin_base {
                 $moodleattributes[$field] = $this->config->{"field_map_$field"};
             }
         }
+        $moodleattributes['username'] = $this->config->fielduser;
         return $moodleattributes;
     }
 

auth/ldap/auth.php

@@ -1489,6 +1489,7 @@ class auth_plugin_ldap extends auth_plugin_base {
                 }
             }
         }
+        $moodleattributes['username'] = $this->config->user_attribute;
         return $moodleattributes;
     }
 

auth/shibboleth/auth.php

@@ -129,6 +129,7 @@ class auth_plugin_shibboleth extends auth_plugin_base {
                 $moodleattributes[$field] = $configarray["field_map_$field"];
             }
         }
+        $moodleattributes['username'] = $configarray["user_attribute"];
 
         return $moodleattributes;
     }

lib/moodlelib.php

@@ -2605,6 +2605,10 @@ function update_user_record($username, $authplugin) {
     if ($newinfo = $userauth->get_userinfo($username)) {
         $newinfo = truncate_userinfo($newinfo);
         foreach ($newinfo as $key => $value){
+            if ($key === 'username') {
+                // 'username' is not a mapped updateable/lockable field, so skip it.
+                continue;
+            }
             $confval = $userauth->config->{'field_updatelocal_' . $key};
             $lockval = $userauth->config->{'field_lock_' . $key};
             if (empty($confval) || empty($lockval)) {