exp: Preserve staged changes after experiments.

- Detach head after stashing workspace.
- Use reinstate_index.

dvc/repo/experiments/__init__.py

@@ -96,19 +96,9 @@ class Experiments:
     def reproduce_one(
         self,
         tmp_dir: bool = False,
-        machine: Optional[str] = None,
         **kwargs,
     ):
         """Reproduce and checkout a single (standalone) experiment."""
-        if not (tmp_dir or machine):
-            staged, _, _ = self.scm.status(untracked_files="no")
-            if staged:
-                logger.warning(
-                    "Your workspace contains staged Git changes which will be "
-                    "unstaged before running this experiment."
-                )
-                self.scm.reset()
-
         exp_queue: "BaseStashQueue" = (
             self.tempdir_queue if tmp_dir else self.workspace_queue
         )

dvc/repo/experiments/queue/base.py

@@ -323,12 +323,12 @@ class BaseStashQueue(ABC):
         .. _Hydra Override:
             https://hydra.cc/docs/next/advanced/override_grammar/basic/
         """
-        with self.scm.detach_head(client="dvc") as orig_head:
-            stash_head = orig_head
-            if baseline_rev is None:
-                baseline_rev = orig_head
+        with self.scm.stash_workspace(reinstate_index=True) as workspace:
+            with self.scm.detach_head(client="dvc") as orig_head:
+                stash_head = orig_head
+                if baseline_rev is None:
+                    baseline_rev = orig_head
 
-            with self.scm.stash_workspace() as workspace:
                 try:
                     if workspace:
                         self.stash.apply(workspace)

tests/func/experiments/test_stash_exp.py

@@ -3,11 +3,15 @@ import logging
 import pytest
 from funcy import first
 
+from dvc.exceptions import ReproductionError
+
 
-@pytest.mark.xfail(reason="TODO: https://github.com/iterative/dvc/issues/6297")
 @pytest.mark.parametrize("tmp", [True, False])
 @pytest.mark.parametrize("staged", [True, False])
 def test_deleted(tmp_dir, scm, dvc, caplog, tmp, staged):
+    if not tmp:
+        pytest.xfail("TODO: https://github.com/iterative/dvc/issues/6297")
+
     tmp_dir.scm_gen("file", "file", commit="commit file")
     stage = dvc.stage.add(
         cmd="cat file",
@@ -21,9 +25,9 @@ def test_deleted(tmp_dir, scm, dvc, caplog, tmp, staged):
         scm.add(["file"])
 
     with caplog.at_level(logging.ERROR):
-        results = dvc.experiments.run(stage.addressing, tmp_dir=tmp)
-        assert "Failed to reproduce experiment" in caplog.text
-        assert not results
+        with pytest.raises(ReproductionError):
+            dvc.experiments.run(stage.addressing, tmp_dir=tmp)
+        assert "failed to reproduce 'foo'" in caplog.text
 
     assert not file.exists()
 
@@ -51,8 +55,6 @@ def test_modified(tmp_dir, scm, dvc, caplog, tmp, staged):
 
 @pytest.mark.parametrize("tmp", [True, False])
 def test_staged_new_file(tmp_dir, scm, dvc, tmp):
-    if not tmp:
-        pytest.xfail("TODO: https://github.com/iterative/dvc/issues/8998")
     stage = dvc.stage.add(
         cmd="cat file",
         name="foo",