Issue #15767: Revert 3a50025f1900 for ModuleNotFoundError

Python/errors.c

@@ -619,25 +619,12 @@ PyObject *PyErr_SetFromWindowsErrWithUnicodeFilename(
 #endif /* MS_WINDOWS */
 
 PyObject *
-PyErr_SetImportErrorSubclass(PyObject *exception, PyObject *msg,
-    PyObject *name, PyObject *path)
+PyErr_SetImportError(PyObject *msg, PyObject *name, PyObject *path)
 {
-    int issubclass;
     PyObject *args, *kwargs, *error;
 
-    issubclass = PyObject_IsSubclass(exception, PyExc_ImportError);
-    if (issubclass < 0) {
+    if (msg == NULL)
         return NULL;
-    }
-    else if (!issubclass) {
-        PyErr_SetString(PyExc_TypeError, "expected a subclass of ImportError");
-        return NULL;
-    }
-
-    if (msg == NULL) {
-        PyErr_SetString(PyExc_TypeError, "expected a message argument");
-        return NULL;
-    }
 
     args = PyTuple_New(1);
     if (args == NULL)
@@ -662,7 +649,7 @@ PyErr_SetImportErrorSubclass(PyObject *exception, PyObject *msg,
     PyDict_SetItemString(kwargs, "name", name);
     PyDict_SetItemString(kwargs, "path", path);
 
-    error = PyObject_Call(exception, args, kwargs);
+    error = PyObject_Call(PyExc_ImportError, args, kwargs);
     if (error != NULL) {
         PyErr_SetObject((PyObject *)Py_TYPE(error), error);
         Py_DECREF(error);
@@ -674,12 +661,6 @@ PyErr_SetImportErrorSubclass(PyObject *exception, PyObject *msg,
     return NULL;
 }
 
-PyObject *
-PyErr_SetImportError(PyObject *msg, PyObject *name, PyObject *path)
-{
-    return PyErr_SetImportErrorSubclass(PyExc_ImportError, msg, name, path);
-}
-
 void
 _PyErr_BadInternalCall(const char *filename, int lineno)
 {

Python/import.c

@@ -1428,8 +1428,7 @@ PyImport_ImportModuleLevelObject(PyObject *name, PyObject *given_globals,
         PyObject *msg = PyUnicode_FromFormat("import of %R halted; "
                                              "None in sys.modules", abs_name);
         if (msg != NULL) {
-            PyErr_SetImportErrorSubclass(PyExc_ModuleNotFoundError, msg,
-                    abs_name, NULL);
+            PyErr_SetImportError(msg, abs_name, NULL);
             Py_DECREF(msg);
         }
         mod = NULL;