put the _process_deque into an action too

src/allmydata/test/test_magic_folder.py

@@ -1100,6 +1100,7 @@ class MagicFolderAliceBobTestMixin(MagicFolderCLITestMixin, ShouldFailMixin, Rea
         # now let bob try to do the download.  Reach in and call
         # _process_deque directly because we are already half-way through a
         # logical iteration thanks to the _perform_scan call above.
+        with start_action(action_type=u"test:process-deque"):
             yield self.bob_magicfolder.downloader._process_deque()
 
             self.eliot_logger.flushTracebacks(UnrecoverableFileError)