diff -r 2959c3e986e0 -r bd872f64a8ba mercurial/node.py
--- a/mercurial/node.py	Sat May 06 04:51:25 2017 +0530
+++ b/mercurial/node.py	Fri Feb 10 16:56:29 2017 -0800
@@ -23,7 +23,7 @@
 addednodeid = ('0' * 15) + 'added'
 modifiednodeid = ('0' * 12) + 'modified'
 
-wdirnodes = set((newnodeid, addednodeid, modifiednodeid))
+wdirnodes = {newnodeid, addednodeid, modifiednodeid}
 
 # pseudo identifiers for working directory
 # (they are experimental, so don't add too many dependencies on them)