Fix one more get_url_for_data_file

Change-Id: I22d556fe4719fc8e7b53c66b778f6b4196f8f024
Reviewed-on: https://gerrit.libreoffice.org/70523
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

uitest/UITest_demo_ui.mk

@@ -13,4 +13,8 @@ $(eval $(call gb_UITest_add_modules,demo_ui,$(SRCDIR)/uitest,\
 	demo_ui/ \
 ))
 
+$(eval $(call gb_UITest_set_defs,demo_ui, \
+    TDOC="$(SRCDIR)/uitest/demo_ui/data" \
+))
+
 # vim: set noet sw=4 ts=4:

uitest/demo_ui/handle_multiple_files.py

@@ -11,13 +11,14 @@ from libreoffice.uno.eventlistener import EventListener
 from uitest.framework import UITestCase
 
 from uitest.debug import sleep
-from uitest.path import get_srcdir_url
 
 import time
+import org.libreoffice.unotest
 import os
+import pathlib
 
 def get_url_for_data_file(file_name):
-    return get_srcdir_url() + "/uitest/demo_ui/data/" + file_name
+    return pathlib.Path(org.libreoffice.unotest.makeCopyFromTDOC(file_name)).as_uri()
 
 class HandleFiles(UITestCase):