site: error on sitecustomize import error

Issue #26099: The site module now writes an error into stderr if sitecustomize
module can be imported but executing the module raise an ImportError. Same
change for usercustomize.

Lib/site.py

@@ -504,9 +504,13 @@ def venv(known_paths):
 def execsitecustomize():
     """Run custom site specific code, if available."""
     try:
-        import sitecustomize
-    except ImportError:
-        pass
+        try:
+            import sitecustomize
+        except ImportError as exc:
+            if exc.name == 'sitecustomize':
+                pass
+            else:
+                raise
     except Exception as err:
         if os.environ.get("PYTHONVERBOSE"):
             sys.excepthook(*sys.exc_info())
@@ -520,9 +524,13 @@ def execsitecustomize():
 def execusercustomize():
     """Run custom user specific code, if available."""
     try:
-        import usercustomize
-    except ImportError:
-        pass
+        try:
+            import usercustomize
+        except ImportError as exc:
+            if exc.name == 'usercustomize':
+                pass
+            else:
+                raise
     except Exception as err:
         if os.environ.get("PYTHONVERBOSE"):
             sys.excepthook(*sys.exc_info())

Misc/NEWS

@@ -146,6 +146,10 @@ Core and Builtins
 Library
 -------
 
+- Issue #26099: The site module now writes an error into stderr if
+  sitecustomize module can be imported but executing the module raise an
+  ImportError. Same change for usercustomize.
+
 - Issue #26147: xmlrpc now works with strings not encodable with used
   non-UTF-8 encoding.