YQL-19866: Do not release the finished state

commit_hash:3c10c54803265211cf64d4c98705be92ef0c8486

Author: igormunkin

yql/essentials/minikql/comp_nodes/mkql_todict.cpp

@@ -985,7 +985,7 @@ class TSqueezeSetFlowWrapper : public TStatefulFlowCodegeneratorNode<TSqueezeSet
 
     NUdf::TUnboxedValuePod DoCalculate(NUdf::TUnboxedValue& state, TComputationContext& ctx) const {
         if (state.IsFinish()) {
-            return state.Release();
+            return state;
         } else if (state.IsInvalid()) {
             MakeState(ctx, state);
         }
@@ -1162,7 +1162,7 @@ class TSqueezeSetWideWrapper : public TStatefulFlowCodegeneratorNode<TSqueezeSet
 
     NUdf::TUnboxedValuePod DoCalculate(NUdf::TUnboxedValue& state, TComputationContext& ctx) const {
         if (state.IsFinish()) {
-            return state.Release();
+            return state;
         } else if (state.IsInvalid()) {
             MakeState(ctx, state);
         }

yql/essentials/minikql/comp_nodes/ut/mkql_todict_ut.cpp

@@ -147,6 +147,10 @@ Y_UNIT_TEST_SUITE(TMiniKQLToDictTest) {
 
             status = res.Fetch(v);
             UNIT_ASSERT_VALUES_EQUAL(NUdf::EFetchStatus::Finish, status);
+            // XXX: Check whether the internal state is not released
+            // and the sentinel is still set (see more info in YQL-19866).
+            status = res.Fetch(v);
+            UNIT_ASSERT_VALUES_EQUAL(NUdf::EFetchStatus::Finish, status);
         };
 
         for (auto stream : {true, false}) {
@@ -201,6 +205,10 @@ Y_UNIT_TEST_SUITE(TMiniKQLToDictTest) {
 
             status = res.Fetch(v);
             UNIT_ASSERT_VALUES_EQUAL(NUdf::EFetchStatus::Finish, status);
+            // XXX: Check whether the internal state is not released
+            // and the sentinel is still set (see more info in YQL-19866).
+            status = res.Fetch(v);
+            UNIT_ASSERT_VALUES_EQUAL(NUdf::EFetchStatus::Finish, status);
         };
 
         for (auto hashed : {true, false}) {