Issue #27352: Correct the validation of the ImportFrom AST node and simplify

the implementation of the IMPORT_NAME opcode.

Python/ast.c

@@ -475,8 +475,8 @@ validate_stmt(stmt_ty stmt)
     case Import_kind:
         return validate_nonempty_seq(stmt->v.Import.names, "names", "Import");
     case ImportFrom_kind:
-        if (stmt->v.ImportFrom.level < -1) {
-            PyErr_SetString(PyExc_ValueError, "ImportFrom level less than -1");
+        if (stmt->v.ImportFrom.level < 0) {
+            PyErr_SetString(PyExc_ValueError, "Negative ImportFrom level");
             return 0;
         }
         return validate_nonempty_seq(stmt->v.ImportFrom.names, "names", "ImportFrom");

Python/ceval.c

@@ -2820,7 +2820,6 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
             Py_INCREF(func);
             from = POP();
             level = TOP();
-            if (PyLong_AsLong(level) != -1 || PyErr_Occurred())
             args = PyTuple_Pack(5,
                             name,
                             f->f_globals,
@@ -2828,13 +2827,6 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
                                   Py_None : f->f_locals,
                             from,
                             level);
-            else
-                args = PyTuple_Pack(4,
-                            name,
-                            f->f_globals,
-                            f->f_locals == NULL ?
-                                  Py_None : f->f_locals,
-                            from);
             Py_DECREF(level);
             Py_DECREF(from);
             if (args == NULL) {