Merge branch 'ar/unlink-err' into maint

* ar/unlink-err:
  print unlink(2) errno in copy_or_link_directory
  replace direct calls to unlink(2) with unlink_or_warn
  Introduce an unlink(2) wrapper which gives warning if unlink failed

builtin-fetch-pack.c

@@ -825,7 +825,7 @@ struct ref *fetch_pack(struct fetch_pack_args *my_args,
 		fd = hold_lock_file_for_update(&lock, shallow,
 					       LOCK_DIE_ON_ERROR);
 		if (!write_shallow_commits(fd, 0)) {
-			unlink(shallow);
+			unlink_or_warn(shallow);
 			rollback_lock_file(&lock);
 		} else {
 			commit_lock_file(&lock);