Issue #18200: Update the stdlib (except tests) to use
ModuleNotFoundError.
diff --git a/Lib/lib2to3/refactor.py b/Lib/lib2to3/refactor.py
index 8100317..11a353c 100644
--- a/Lib/lib2to3/refactor.py
+++ b/Lib/lib2to3/refactor.py
@@ -706,7 +706,7 @@
                 items, write, doctests_only)
         try:
             import multiprocessing
-        except ImportError:
+        except ModuleNotFoundError:
             raise MultiprocessingUnsupported
         if self.queue is not None:
             raise RuntimeError("already doing multiple processes")