Merge branch 'py/diff-submodule'

* py/diff-submodule:
  is_racy_timestamp(): do not check timestamp for gitlinks
  diff-lib.c: rename check_work_tree_entity()
  diff: a submodule not checked out is not modified
  Add t7506 to test submodule related functions for git-status
  t4027: test diff for submodule with empty directory

read-cache.c

@@ -198,7 +198,8 @@ static int ce_match_stat_basic(struct cache_entry *ce, struct stat *st)
 
 static int is_racy_timestamp(const struct index_state *istate, struct cache_entry *ce)
 {
-	return (istate->timestamp &&
+	return (!S_ISGITLINK(ce->ce_mode) &&
+		istate->timestamp &&
 		((unsigned int)istate->timestamp) <= ce->ce_mtime);
 }