gh-136438: Make sure test_interpreters pass with all optimization levels

Author: donbarbos

Lib/concurrent/interpreters/_crossinterp.py

@@ -40,8 +40,10 @@ class UnboundItem:
 
     @classonly
     def singleton(cls, kind, module, name='UNBOUND'):
-        doc = cls.__doc__.replace('cross-interpreter container', kind)
-        doc = doc.replace('cross-interpreter', kind)
+        doc = cls.__doc__
+        if doc:
+            doc = doc.replace('cross-interpreter container', kind)
+            doc = doc.replace('cross-interpreter', kind)
         subclass = type(
             f'Unbound{kind.capitalize()}Item',
             (cls,),

Lib/test/test_interpreters/test_api.py

@@ -776,7 +776,7 @@ def test_created_with_capi(self):
             with self.assertRaisesRegex(InterpreterError, 'unrecognized'):
                 interp.prepare_main({'spam': True})
             with self.assertRaisesRegex(ExecutionFailed, 'NameError'):
-                self.run_from_capi(interpid, 'assert spam is True')
+                self.run_from_capi(interpid, 'spam')
 
 
 class TestInterpreterExec(TestBase):