fix error message for git files

dvc/repo/get.py

@@ -8,6 +8,7 @@ from dvc.exceptions import GetDVCFileError
 from dvc.exceptions import NotDvcRepoError
 from dvc.exceptions import OutputNotFoundError
 from dvc.exceptions import UrlNotDvcRepoError
+from dvc.exceptions import FileMissingError
 from dvc.external_repo import external_repo
 from dvc.path_info import PathInfo
 from dvc.stage import Stage
@@ -18,14 +19,28 @@ from dvc.utils.fs import remove
 logger = logging.getLogger(__name__)
 
 
+def _is_git_file(repo, path):
+    if not os.path.isabs(path):
+        try:
+            output = repo.find_out_by_relpath(path)
+            if not output.use_cache:
+                return True
+        except OutputNotFoundError:
+            return True
+    return False
+
+
 def _copy_git_file(repo, src, dst):
     src_full_path = os.path.join(repo.root_dir, src)
     dst_full_path = os.path.abspath(dst)
 
-    if os.path.isdir(src_full_path):
-        shutil.copytree(src_full_path, dst_full_path)
-    else:
-        shutil.copy2(src_full_path, dst_full_path)
+    try:
+        if os.path.isdir(src_full_path):
+            shutil.copytree(src_full_path, dst_full_path)
+        else:
+            shutil.copy2(src_full_path, dst_full_path)
+    except FileNotFoundError:
+        raise FileMissingError(src)
 
 
 @staticmethod
@@ -44,8 +59,7 @@ def get(url, path, out=None, rev=None):
     tmp_dir = os.path.join(dpath, "." + str(shortuuid.uuid()))
     try:
         with external_repo(cache_dir=tmp_dir, url=url, rev=rev) as repo:
-            full_path = os.path.join(repo.root_dir, path)
-            if os.path.exists(full_path) and not os.path.isabs(path):
+            if _is_git_file(repo, path):
                 _copy_git_file(repo, path, out)
                 return
 

tests/func/test_get.py

@@ -10,6 +10,7 @@ from dvc.config import Config
 from dvc.exceptions import GetDVCFileError
 from dvc.exceptions import UrlNotDvcRepoError
 from dvc.exceptions import NoOutputInExternalRepoError
+from dvc.exceptions import FileMissingError
 from dvc.repo import Repo
 from dvc.system import System
 from dvc.utils import makedirs
@@ -143,11 +144,20 @@ def test_non_cached_output(tmp_path, erepo):
 
 
 # https://github.com/iterative/dvc/pull/2837#discussion_r352123053
-def test_fails_with_non_git_files(erepo):
+def test_fails_with_files_outside_repo(erepo):
     with pytest.raises(NoOutputInExternalRepoError):
         Repo.get(erepo.root_dir, "/root/")
 
 
+def test_fails_with_non_existing_files(erepo):
+    fname = "file_does_not_exist"
+    with pytest.raises(
+        FileMissingError,
+        match="Can't find '{}' neither locally nor on remote".format(fname),
+    ):
+        Repo.get(erepo.root_dir, fname)
+
+
 @pytest.mark.parametrize("dname", [".", "dir", "dir/subdir"])
 def test_get_to_dir(dname, erepo):
     src = erepo.FOO