diff --git a/app/server/lib/NSandbox.ts b/app/server/lib/NSandbox.ts
index 35e09ae1..eb219d88 100644
--- a/app/server/lib/NSandbox.ts
+++ b/app/server/lib/NSandbox.ts
@@ -229,9 +229,11 @@ export class NSandbox implements ISandbox {
       // (or just benign if the doc is big).
       log.rawWarn('Slow pyCall', {...this._logMeta, funcName});
     }, 10000);
-    const result = await this._pyCallWait(funcName, startTime);
-    clearTimeout(slowCallCheck);
-    return result;
+    try {
+      return await this._pyCallWait(funcName, startTime);
+    } finally {
+      clearTimeout(slowCallCheck);
+    }
   }
 
   /**
diff --git a/sandbox/grist/test_renames2.py b/sandbox/grist/test_renames2.py
index d453297f..b57e2aba 100644
--- a/sandbox/grist/test_renames2.py
+++ b/sandbox/grist/test_renames2.py
@@ -1,6 +1,8 @@
 import textwrap
-import logger
+import unittest
 
+import logger
+import six
 import test_engine
 
 log = logger.Logger(__name__, logger.INFO)
@@ -187,6 +189,7 @@ class TestRenames2(test_engine.EngineTestCase):
     self.assertTableData("Games", cols="subset", data=self.games_data)
 
 
+  @unittest.skipUnless(six.PY3, "Python 3 only")
   def test_renames_b(self):
     # Rename Games.name: affects People.Games_Won, Games.win4_game_name
     out_actions = self.apply_user_action(["RenameColumn", "Games", "name", "nombre"])
@@ -260,6 +263,7 @@ class TestRenames2(test_engine.EngineTestCase):
     self.assertTableData("Games", cols="subset", data=self.games_data)
 
 
+  @unittest.skipUnless(six.PY3, "Python 3 only")
   def test_renames_d(self):
     # Rename People.name: affects People.N, People.ParnerNames
     # TODO: PartnerNames does NOT get updated correctly because astroid doesn't infer meanings of
@@ -288,6 +292,7 @@ class TestRenames2(test_engine.EngineTestCase):
     self.assertTableData("Games", cols="subset", data=self.games_data)
 
 
+  @unittest.skipUnless(six.PY3, "Python 3 only")
   def test_renames_e(self):
     # Rename People.partner: affects People.partner4
     # TODO: partner4 ($partner.partner.partner.partner) only gets updated partly because of
@@ -309,6 +314,7 @@ class TestRenames2(test_engine.EngineTestCase):
     self.assertTableData("Games", cols="subset", data=self.games_data)
 
 
+  @unittest.skipUnless(six.PY3, "Python 3 only")
   def test_renames_f(self):
     # Rename People.win -> People.pwin. Make sure only Game.win is not affected.
     out_actions = self.apply_user_action(["RenameColumn", "People", "win", "pwin"])