diff -r e9e7156a8d6c -r 11f284c8c5e4 mercurial/pathutil.py
--- a/mercurial/pathutil.py	Fri Mar 27 10:38:40 2020 -0400
+++ b/mercurial/pathutil.py	Fri Mar 27 10:39:59 2020 -0400
@@ -286,6 +286,9 @@
     '''a multiset of directory names from a set of file paths'''
 
     def __init__(self, map, skip=None):
+        '''
+        a dict map indicates a dirstate while a list indicates a manifest
+        '''
         self._dirs = {}
         addpath = self.addpath
         if isinstance(map, dict) and skip is not None: