erepo: include exp refs in clones

- add test for dvc get --rev=<exp>

dvc/external_repo.py

@@ -3,7 +3,7 @@ import os
 import tempfile
 import threading
 from contextlib import contextmanager
-from typing import Dict
+from typing import TYPE_CHECKING, Dict
 
 from funcy import retry, wrap_with
 
@@ -19,6 +19,9 @@ from dvc.repo import Repo
 from dvc.scm import CloneError, map_scm_exception
 from dvc.utils import relpath
 
+if TYPE_CHECKING:
+    from scmrepo import Git
+
 logger = logging.getLogger(__name__)
 
 
@@ -201,14 +204,12 @@ def _clone_default_branch(url, rev, for_write=False):
                     # given repo URL it is easier/safer for us to work with
                     # full clones in this case.
                     logger.debug("erepo: unshallowing clone for '%s'", url)
-                    git.fetch(unshallow=True)
-                    _merge_upstream(git)
+                    _pull(git, unshallow=True)
                     shallow = False
                     CLONES[url] = (clone_path, shallow)
                 else:
                     logger.debug("erepo: git pull '%s'", url)
-                    git.fetch()
-                    _merge_upstream(git)
+                    _pull(git)
         else:
             from dvc.scm import clone
 
@@ -227,7 +228,9 @@ def _clone_default_branch(url, rev, for_write=False):
                             "erepo: using shallow clone for branch '%s'", rev
                         )
                 except CloneError:
-                    pass
+                    git_dir = os.path.join(clone_path, ".git")
+                    if os.path.exists(git_dir):
+                        _remove(git_dir)
             if not git:
                 git = clone(url, clone_path)
                 shallow = False
@@ -239,7 +242,15 @@ def _clone_default_branch(url, rev, for_write=False):
     return clone_path, shallow
 
 
-def _merge_upstream(git):
+def _pull(git: "Git", unshallow: bool = False):
+    from dvc.repo.experiments.utils import fetch_all_exps
+
+    git.fetch(unshallow=unshallow)
+    _merge_upstream(git)
+    fetch_all_exps(git, "origin")
+
+
+def _merge_upstream(git: "Git"):
     from scmrepo.exceptions import SCMError
 
     try:

dvc/repo/experiments/utils.py

@@ -191,3 +191,16 @@ def check_ref_format(scm: "Git", ref: ExpRefInfo):
             f"Invalid exp name {ref.name}, the exp name must follow rules in "
             "https://git-scm.com/docs/git-check-ref-format"
         )
+
+
+def fetch_all_exps(scm: "Git", url: str, progress: Optional[Callable] = None):
+    refspecs = [
+        f"{ref}:{ref}"
+        for ref in iter_remote_refs(scm, url, base=EXPS_NAMESPACE)
+        if not (ref.startswith(EXEC_NAMESPACE) or ref == EXPS_STASH)
+    ]
+    scm.fetch_refspecs(
+        url,
+        refspecs,
+        progress=progress,
+    )

dvc/scm.py

@@ -101,9 +101,14 @@ class TqdmGit(Tqdm):
 def clone(url: str, to_path: str, **kwargs):
     from scmrepo.exceptions import CloneError as InternalCloneError
 
+    from dvc.repo.experiments.utils import fetch_all_exps
+
     with TqdmGit(desc="Cloning") as pbar:
         try:
-            return Git.clone(url, to_path, progress=pbar.update_git, **kwargs)
+            git = Git.clone(url, to_path, progress=pbar.update_git, **kwargs)
+            if "shallow_branch" not in kwargs:
+                fetch_all_exps(git, "origin", progress=pbar.update_git)
+            return git
         except InternalCloneError as exc:
             raise CloneError(str(exc))
 

tests/func/experiments/test_remote.py

@@ -374,3 +374,20 @@ def test_auth_error_push(tmp_dir, scm, dvc, exp_stage, http_auth_patch):
         match=f"HTTP Git authentication is not supported: '{http_auth_patch}'",
     ):
         dvc.experiments.push(http_auth_patch, [ref_info.name])
+
+
+@pytest.mark.parametrize("use_ref", [True, False])
+def test_get(tmp_dir, scm, dvc, exp_stage, erepo_dir, use_ref):
+    from dvc.repo import Repo
+
+    results = dvc.experiments.run(exp_stage.addressing, params=["foo=2"])
+    exp_rev = first(results)
+    exp_ref = first(exp_refs_by_rev(scm, exp_rev))
+
+    with erepo_dir.chdir():
+        Repo.get(
+            str(tmp_dir),
+            "params.yaml",
+            rev=exp_ref.name if use_ref else exp_rev,
+        )
+        assert (erepo_dir / "params.yaml").read_text().strip() == "foo: 2"