[PATCH] dirstate: add docstring for invalidate

[Siddharth Agarwal]

# HG changeset patch
# User Siddharth Agarwal <sid0 at fb.com>
# Date 1496617730 25200
#      Sun Jun 04 16:08:50 2017 -0700
# Node ID 45841cedb603b93803eec37bd7d01456a6b8e812
# Parent  5277d6faabb4f9593a5d33cdab6c4a6191ad856d
dirstate: add docstring for invalidate

This always confuses me, and we already have a docstring on
localrepo.invalidatedirstate.

diff --git a/mercurial/dirstate.py b/mercurial/dirstate.py
--- a/mercurial/dirstate.py
+++ b/mercurial/dirstate.py
@@ -470,6 +470,12 @@ class dirstate(object):
             self._pl = p
 
     def invalidate(self):
+        '''Causes the next access to reread the dirstate.
+
+        This is different from localrepo.invalidatedirstate() because it always
+        rereads the dirstate. Use localrepo.invalidatedirstate() if you want to
+        check whether the dirstate has changed before rereading it.'''
+
         for a in ("_map", "_copymap", "_filefoldmap", "_dirfoldmap", "_branch",
                   "_pl", "_dirs", "_ignore", "_nonnormalset",
                   "_otherparentset"):