fix: read the refusal wording from _install

tests/test_install_experience.py

@@ -1163,7 +1163,7 @@ class ADetectedClosedFolderSaysWhereItCameFrom(unittest.TestCase):
 
     def test_an_assumed_default_reads_plainly(self):
         self.assertIn("used by default, since {display_name(name)} was not found",
-                      _source_of(install._run_text))
+                      _source_of(install._install))
 
 
 def _source_of(function) -> str: