get_ref: Fix annotated tags (#10)

* dulwich: Use `get_peeled` for Tags

Fixes `get_ref` for annotated tags.

Closes iterative/dvc#6383

* pygit2: Use `peel` for annotted tags in `get_ref`.

Fixes `get_ref` for annotated tags.

scmrepo/git/backend/dulwich/__init__.py

@@ -334,6 +334,7 @@ def set_ref(
             raise SCMError(f"Failed to set '{name}'")
 
     def get_ref(self, name, follow: bool = True) -> Optional[str]:
+        from dulwich.objects import Tag
         from dulwich.refs import parse_symref_value
 
         name_b = os.fsencode(name)
@@ -350,6 +351,8 @@ def get_ref(self, name, follow: bool = True) -> Optional[str]:
             except ValueError:
                 pass
         if ref:
+            if ref in self.repo and isinstance(self.repo[ref], Tag):
+                ref = self.repo.get_peeled(name_b)
             return os.fsdecode(ref)
         return None
 

scmrepo/git/backend/pygit2.py

@@ -317,13 +317,20 @@ def set_ref(
             )
 
     def get_ref(self, name, follow: bool = True) -> Optional[str]:
-        from pygit2 import GIT_REF_SYMBOLIC
+        from pygit2 import GIT_OBJ_COMMIT, GIT_REF_SYMBOLIC, Tag
 
         ref = self.repo.references.get(name)
         if not ref:
             return None
         if follow and ref.type == GIT_REF_SYMBOLIC:
             ref = ref.resolve()
+        try:
+            obj = self.repo[ref.target]
+            if isinstance(obj, Tag):
+                return str(obj.peel(GIT_OBJ_COMMIT).id)
+        except ValueError:
+            pass
+
         return str(ref.target)
 
     def remove_ref(self, name: str, old_ref: Optional[str] = None):

tests/test_git.py

@@ -280,9 +280,12 @@ def test_get_ref(tmp_dir: TmpDir, scm: Git, git: Git):
             ): "ref: refs/heads/master",
         }
     )
+    scm.tag(["-a", "annotated", "-m", "Annotated Tag"])
 
     assert init_rev == git.get_ref("refs/foo/bar")
     assert init_rev == git.get_ref("refs/foo/baz")
+    assert init_rev == git.get_ref("refs/tags/annotated", follow=True)
+    assert init_rev == git.get_ref("refs/tags/annotated", follow=False)
     assert git.get_ref("refs/foo/baz", follow=False) == "refs/heads/master"
     assert git.get_ref("refs/foo/qux") is None