fix issue of not getting the correct set of merge samples in NTuplePorcessTool

quickstats/_version.py

-__version__ = "0.6.4.0"
+__version__ = "0.6.4.1"

quickstats/analysis/ntuple_process_tool.py

@@ -75,7 +75,7 @@ class NTupleProcessTool(ConfigurableObject):
             # fill missing samples
             for sample in self.all_samples:
                 if ((sample not in merge_samples) and 
-                    all(sample not in _samples for _samples in merge_samples)):
+                    all(sample not in _samples for _samples in merge_samples.values())):
                     self.all_merged_samples.append(sample)
         
     def load_processor_config(self, config_path:str,