stage: monitor: don't forget to unprotect outs (#6134)

Fixes #6083

dvc/stage/monitor.py

@@ -75,6 +75,7 @@ class CheckpointTask(MonitorTask):
     def _run_callback(stage, callback_func):
         stage.save(allow_missing=True)
         stage.commit(allow_missing=True)
+        stage.unprotect_outs()
         logger.debug("Running checkpoint callback for stage '%s'", stage)
         callback_func()
 

tests/func/experiments/test_checkpoints.py

@@ -7,9 +7,13 @@ from dvc.repo.experiments.base import EXEC_APPLY, EXEC_CHECKPOINT
 
 
 @pytest.mark.parametrize("workspace", [True, False])
+@pytest.mark.parametrize("links", ["reflink,copy", "hardlink,symlink"])
 def test_new_checkpoint(
-    tmp_dir, scm, dvc, checkpoint_stage, mocker, workspace
+    tmp_dir, scm, dvc, checkpoint_stage, mocker, workspace, links
 ):
+    with dvc.config.edit() as conf:
+        conf["cache"]["type"] = links
+
     new_mock = mocker.spy(dvc.experiments, "new")
     results = dvc.experiments.run(
         checkpoint_stage.addressing, params=["foo=2"], tmp_dir=not workspace