bugfix!

CHANGELOG.md

 # v2.4.3
 
 * better test coverage
+* bugfix release - add_labels would modify the result's hash!
 
 # v2.4.2
 

satella/__init__.py

-__version__ = '2.4.3rc1'
+__version__ = '2.4.3'

satella/instrumentation/metrics/data.py

@@ -63,8 +63,11 @@ class MetricData(JSONAble):
 
 class MetricDataCollection(JSONAble):
     def add_labels(self, labels: dict) -> None:
+        output = set()
         for child in self.values:
             child.add_labels(labels)
+            output.add(child)
+        self.values = output
 
     def __repr__(self):
         return 'MetricDataCollection(%s)' % (repr(self.values, ))