make sure DBEncryptedFileMetadataManager closes db connection

lbrynet/lbry_file/EncryptedFileMetadataManager.py

@@ -24,7 +24,7 @@ class DBEncryptedFileMetadataManager(object):
         return self._open_db()
 
     def stop(self):
-        self.db_conn = None
+        self.db_conn.close()
         return defer.succeed(True)
 
     def get_all_streams(self):

tests/unit/lbryfile/test_EncryptedFileMetadataManager.py

@@ -14,6 +14,7 @@ class DBEncryptedFileMetadataManagerTest(unittest.TestCase):
         self.manager = DBEncryptedFileMetadataManager(self.db_dir)
 
     def tearDown(self):
+        self.manager.stop()
         shutil.rmtree(self.db_dir)
 
     @defer.inlineCallbacks