data_item: handle __eq__ if other == None

Currently it is not possible to check if data_item == None,
as __eq__ tries to access .data in 'None' object and thus
throws an exception.

Signed-off-by: Ruslan Kuprieiev <[email protected]>

dvc/path/data_item.py

@@ -62,6 +62,9 @@ class DataItem(object):
         return self.data.dvc.__hash__()
 
     def __eq__(self, other):
+        if other == None:
+            return False
+
         return self.data.dvc == other.data.dvc
 
     @property