Dict: fix the __eq__ implementation to call super

The `__eq__` method was recently implemented for the `Dict` data type
but it erroneously did not call through to the super implementation in
case the dictionary content does not match that of `other`. This caused
the fallback equality implemented on the `Node` base class, which
ensures that two nodes with the same UUID compare equal, to be missed.

aiida/orm/nodes/data/dict.py

@@ -8,7 +8,6 @@
 # For further information please visit http://www.aiida.net               #
 ###########################################################################
 """`Data` sub class to represent a dictionary."""
-
 import copy
 
 from aiida.common import exceptions
@@ -75,7 +74,7 @@ def __eq__(self, other):
         if isinstance(other, dict):
             return self.get_dict() == other
 
-        return self is other
+        return super().__eq__(other)
 
     def set_dict(self, dictionary):
         """ Replace the current dictionary with another one.

tests/orm/data/test_dict.py

@@ -95,3 +95,14 @@ def test_eq(dictionary):
     assert node is node  # pylint: disable=comparison-with-itself
     assert node == dictionary
     assert node != clone
+
+    # To test the fallback, where two ``Dict`` nodes are equal if their UUIDs are even if the content is different, we
+    # create a different node with other content, but artificially give it the same UUID as ``node``. In practice this
+    # wouldn't happen unless, by accident, two different nodes get the same UUID, the probability of which is minimal.
+    # Note that we have to set the UUID directly through the database model instance of the backend entity, since it is
+    # forbidden to change it through the front-end or backend entity instance, for good reasons.
+    other = Dict(dict={})
+    other.backend_entity._dbmodel.uuid = node.uuid  # pylint: disable=protected-access
+    assert other.uuid == node.uuid
+    assert other.dict != node.dict
+    assert node == other