use ZConfig.loadConfigFile to workaround urlib.request.urlopen regression on Windows

Author: jamadden

CHANGES.rst

@@ -11,6 +11,15 @@
 
      This will be the last RelStorage release to support Python 3.9.
 
+  .. warning::
+
+     Current releases of ``persistent``, up through at least 6.1.1,
+     do not properly invalidate objects on Python 3.14. Most
+     applications probably won't notice, but there may be issues with
+     blobs, or if applications have a particular reliance on
+     ``__dict__`` being immediately cleared after an object is
+     invalidated. See `PR 221 <https://github.com/zopefoundation/persistent/pull/221>`_.
+
 - Include ``psycopg2`` in the ``postgresql`` extra on CPython 3.13+.
   See :issue:`515`.
 - Increase the minimum supported version of ``mysql-connector-python``

src/relstorage/tests/test_zodbconvert.py

@@ -415,7 +415,13 @@ def _load_zconfig(self):
         schema = ZConfig.loadSchemaFile(StringIO(schema_xml))
 
         self.assertTrue(os.path.exists(self.cfgfile), self.cfgfile)
-        conf, _ = ZConfig.loadConfig(schema, self.cfgfile)
+        with open(self.cfgfile, 'rt', encoding='utf-8') as f:
+            # loadConfig() takes a *URL*, not a path; under the covers, it
+            # calls ``urllib.request.urlopen``. Prior to 3.14, passing
+            # a path to this function worked fine everywhere. In 3.14,
+            # they broke this on Windows, and it now complains
+            # "Can't open network file \\\\c:\...". So do it for them.
+            conf, _ = ZConfig.loadConfigFile(schema, f)
 
         return conf