external_repo: do not try too hard to fix upstream (iterative#3512)

* tests: importing from bare repo

* external_repo: don't try too hard to set upstream repo especially if url is not a dvc repo.

* Update tests/func/test_import.py

* Add a comment regarding bare-repo clone

dvc/external_repo.py

@@ -127,9 +127,17 @@ def _fix_upstream(self):
         if not os.path.isdir(self.url):
             return
 
-        remote_name = self.config["core"].get("remote")
-        src_repo = Repo(self.url)
         try:
+            src_repo = Repo(self.url)
+        except NotDvcRepoError:
+            # If ExternalRepo does not throw NotDvcRepoError and Repo does,
+            # the self.url might be a bare git repo.
+            # NOTE: This will fail to resolve remote with relative path,
+            # same as if it was a remote DVC repo.
+            return
+
+        try:
+            remote_name = self.config["core"].get("remote")
             if remote_name:
                 self._fix_local_remote(src_repo, remote_name)
             else:

tests/func/test_import.py

@@ -305,3 +305,20 @@ def test_pull_no_rev_lock(erepo_dir, tmp_dir, dvc):
 
     assert (tmp_dir / "foo_imported").is_file()
     assert (tmp_dir / "foo_imported").read_text() == "contents"
+
+
+def test_import_from_bare_git_repo(tmp_dir, make_tmp_dir, erepo_dir):
+    import git
+
+    git.Repo.init(fspath(tmp_dir), bare=True)
+
+    with erepo_dir.chdir():
+        erepo_dir.dvc_gen({"foo": "foo"}, commit="initial")
+        erepo_dir.dvc.push()
+
+        erepo_dir.scm.repo.create_remote("origin", fspath(tmp_dir))
+        erepo_dir.scm.repo.remote("origin").push("master")
+
+    dvc_repo = make_tmp_dir("dvc-repo", scm=True, dvc=True)
+    with dvc_repo.chdir():
+        dvc_repo.dvc.imp(fspath(tmp_dir), "foo")