RepoDependency: never changed

dvc/dependency/repo.py

@@ -98,3 +98,9 @@ def update(self, rev=None):
 
         with self._make_repo(locked=False) as repo:
             self.def_repo[self.PARAM_REV_LOCK] = repo.get_rev()
+
+    def changed_checksum(self):
+        # From current repo point of view what describes RepoDependency is its
+        # origin project url and rev_lock, and it makes RepoDependency
+        # immutable, hence its impossible for checksum to change.
+        return False

dvc/tree/base.py

@@ -245,7 +245,9 @@ def is_dir_hash(cls, hash_):
         return hash_.endswith(cls.CHECKSUM_DIR_SUFFIX)
 
     def get_hash(self, path_info, tree=None, **kwargs):
-        assert isinstance(path_info, str) or path_info.scheme == self.scheme
+        assert path_info and (
+            isinstance(path_info, str) or path_info.scheme == self.scheme
+        )
 
         if not tree:
             tree = self

tests/func/test_commit.py

@@ -1,3 +1,5 @@
+from os import fspath
+
 import pytest
 
 from dvc.dvcfile import PIPELINE_FILE
@@ -95,3 +97,13 @@ def test_commit_pipeline_stage(tmp_dir, dvc, run_copy):
     assert dvc.commit(f":{stage.addressing}") == [stage]
     assert dvc.commit(f"{PIPELINE_FILE}:{stage.addressing}") == [stage]
     assert dvc.commit(PIPELINE_FILE) == [stage]
+
+
+def test_imported_entries_unchanged(tmp_dir, dvc, erepo_dir):
+    with erepo_dir.chdir():
+        erepo_dir.dvc_gen("file", "file content", "initial commit")
+
+    stage = dvc.imp(fspath(erepo_dir), "file")
+
+    with dvc.state:
+        assert stage.changed_entries() == ([], [], None)