XXX hack so that the kopano-backup process does not hang

Index: ECtools/backup/kopano_backup/__init__.py
--- ECtools/backup/kopano_backup/__init__.py.orig
+++ ECtools/backup/kopano_backup/__init__.py
@@ -144,6 +144,8 @@ class BackupWorker(kopano.Worker):
     def main(self):
         config, server, options = self.service.config, self.service.server, self.service.options
         while True:
+            if self.iqueue.empty():
+                continue
             stats = {'changes': 0, 'deletes': 0, 'errors': 0}
             self.service.stats = stats # XXX generalize
             with log_exc(self.log, stats):
