Close the file before trying to remove the directory so it works on Windows.

As reported by Trent Nelson on python-dev.

Lib/bsddb/test/test_basics.py

@@ -97,8 +97,9 @@ class BasicTestCase(unittest.TestCase):
     def tearDown(self):
         self.d.close()
         if self.env is not None:
-            test_support.rmtree(self.homeDir)
             self.env.close()
+            test_support.rmtree(self.homeDir)
+            ## XXX(nnorwitz): is this comment stil valid?
             ## Make a new DBEnv to remove the env files from the home dir.
             ## (It can't be done while the env is open, nor after it has been
             ## closed, so we make a new one to do it.)