Merge branch 'fix-DataObjectHandleBase' into 'master'

Do not modify DataObjectHandleBase python binding on add

See merge request !342

GaudiKernel/python/GaudiKernel/DataObjectHandleBase.py

@@ -41,12 +41,12 @@ class DataObjectHandleBase(object):
         return self.__str__()
 
     def __add__(self,other):
-        self.Path = ':'.join( i + other for i in self.Path.split(':'))
-        return self
+        path = ':'.join( i + other for i in self.Path.split(':'))
+        return DataObjectHandleBase(path)
 
     def __radd__(self,other):
-        self.Path = ':'.join( other + i for i in self.Path.split(':'))
-        return self
+        path = ':'.join( other + i for i in self.Path.split(':'))
+        return DataObjectHandleBase(path)
 
     def __iadd__(self,other):
         self.Path = ':'.join( i + other for i in self.Path.split(':'))