Merge branch 'jc/attr-source-tree'

"git --attr-source=<tree> cmd $args" is a new way to have any
command to read attributes not from the working tree but from the
given tree object.

* jc/attr-source-tree:
  attr: teach "--attr-source=<tree>" global option to "git"

convert.c

@@ -1315,7 +1315,7 @@ void convert_attrs(struct index_state *istate,
 		git_config(read_convert_config, NULL);
 	}
 
-	git_check_attr(istate, NULL, path, check);
+	git_check_attr(istate, path, check);
 	ccheck = check->items;
 	ca->crlf_action = git_path_check_crlf(ccheck + 4);
 	if (ca->crlf_action == CRLF_UNDEFINED)