Make test work under 32-bit systems, and when invoked through Lib/test/regrtest.py

(rather than `-m test.regrtest`)

Lib/test/test_import.py

@@ -313,14 +313,22 @@ class ImportTests(unittest.TestCase):
     def test_timestamp_overflow(self):
         # A modification timestamp larger than 2**32 should not be a problem
         # when importing a module (issue #11235).
+        sys.path.insert(0, os.curdir)
+        try:
             source = TESTFN + ".py"
             compiled = imp.cache_from_source(source)
             with open(source, 'w') as f:
                 pass
+            try:
                 os.utime(source, (2 ** 33, 2 ** 33))
+            except OverflowError:
+                self.skipTest("cannot set modification time to large integer")
             __import__(TESTFN)
             # The pyc file was created.
             os.stat(compiled)
+        finally:
+            del sys.path[0]
+            remove_files(TESTFN)
 
 
 class PycRewritingTests(unittest.TestCase):