Issue #15828: Don't try to close a file if imp.find_module() doesn't

return one.

Lib/test/test_imp.py

@@ -211,7 +211,9 @@ class ImportTests(unittest.TestCase):
         # and importlib couldn't handle C extensions
         example = "_heapq"
         x = imp.find_module(example)
-        self.addCleanup(x[0].close)
+        file_ = x[0]
+        if file_ is not None:
+            self.addCleanup(file_.close)
         mod = imp.load_module(example, *x)
         self.assertEqual(mod.__name__, example)