Issue #15425: Don't rely on the assumption that the current working directory...

Issue #15425: Don't rely on the assumption that the current working directory is on sys.path (this will hopefully appease the XP buildbots)

Lib/test/test_import.py

@@ -859,16 +859,14 @@ class ImportTracebackTests(unittest.TestCase):
 
     def _setup_broken_package(self, parent, child):
         pkg_name = "_parent_foo"
-        def cleanup():
-            rmtree(pkg_name)
-            unload(pkg_name)
-        os.mkdir(pkg_name)
-        self.addCleanup(cleanup)
+        self.addCleanup(unload, pkg_name)
+        pkg_path = os.path.join(TESTFN, pkg_name)
+        os.mkdir(pkg_path)
         # Touch the __init__.py
-        init_path = os.path.join(pkg_name, '__init__.py')
+        init_path = os.path.join(pkg_path, '__init__.py')
         with open(init_path, 'w') as f:
             f.write(parent)
-        bar_path = os.path.join(pkg_name, 'bar.py')
+        bar_path = os.path.join(pkg_path, 'bar.py')
         with open(bar_path, 'w') as f:
             f.write(child)
         importlib.invalidate_caches()