issue #2440 clear fake user cache on successful login

Added a call to clear_fake_user_cache() in pwg_login to ensure the fake user cache is reset after a successful login. Also introduced the clear_fake_user_cache() function for this purpose.

include/functions_user.inc.php

@@ -1330,6 +1330,7 @@ function pwg_login($success, $username, $password, $remember_me)
     log_user($user_found['id'], $remember_me);
   }
 
+  clear_fake_user_cache();
   trigger_notify('login_success', stripslashes($username));
   return true;
 }
@@ -1409,6 +1410,17 @@ function generate_fake_user()
   return $_SESSION['fake_user_cache'];
 }
 
+/**
+ * Clear current session fake user cache
+ * 
+ * @since 16
+ * @return void
+ */
+function clear_fake_user_cache()
+{
+  unset($_SESSION['fake_user_cache']);
+}
+
 /**
  * Performs all the cleanup on user logout.
  */