--- duplicity/backends/b2backend.py.bak	2018-11-18 00:13:48.175867382 +0100
+++ duplicity/backends/b2backend.py	2018-11-18 00:14:24.785080193 +0100
@@ -32,6 +32,9 @@
 
 
 class B2ProgressListener:
+    def __enter__(self):
+        pass
+    
     def set_total_bytes(self, total_byte_count):
         self.total_byte_count = total_byte_count
 
@@ -41,6 +44,8 @@
     def close(self):
         pass
 
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        pass
 
 class B2Backend(duplicity.backend.Backend):
     """