rollback 005fd1fe31ab (see #14609 and #14582)

Being able to overload a sys.module entry during import of a module was broken
by this changeset.
diff --git a/Python/import.c b/Python/import.c
index 07c3d6f..11d58ae 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -2447,22 +2447,15 @@
             Py_DECREF(partition);
 
             if (level == 0) {
-                if (PyUnicode_GET_LENGTH(name) ==
-                        PyUnicode_GET_LENGTH(front)) {
-                    final_mod = mod;
-                }
-                else {
-                    final_mod = PyDict_GetItem(interp->modules, front);
-                    if (final_mod == NULL) {
-                        PyErr_Format(PyExc_KeyError,
-                                     "%R not in sys.modules as expected", front);
-                    }
-                }
+                final_mod = PyDict_GetItem(interp->modules, front);
                 Py_DECREF(front);
                 if (final_mod == NULL) {
-                    goto error_with_unlock;
+                    PyErr_Format(PyExc_KeyError,
+                                 "%R not in sys.modules as expected", front);
                 }
-                Py_INCREF(final_mod);
+                else {
+                    Py_INCREF(final_mod);
+                }
             }
             else {
                 Py_ssize_t cut_off = PyUnicode_GET_LENGTH(name) -