Concepts bodies are now evaluated on demand

tests/core/test_ExecutionContext.py

@@ -34,6 +34,7 @@ def test_i_can_push():
                          concepts={"bar": Concept("bar")})
     a.preprocess = set()
     a.preprocess.add("preprocess")
+    a.extra_info.append(BuiltinConcepts.CONCEPT_EVAL_REQUESTED)
 
     b = a.push()
 
@@ -49,6 +50,7 @@ def test_i_can_push():
     assert b.id == a.id + 1
     assert b._tab == a._tab + "    "
     assert b.preprocess == a.preprocess
+    assert b.extra_info == [BuiltinConcepts.CONCEPT_EVAL_REQUESTED]
 
 
 def test_children_i_created_when_i_push():