mercurial/ancestor.py

--- a/mercurial/ancestor.py	Sat May 06 04:51:25 2017 +0530
+++ b/mercurial/ancestor.py	Fri Feb 10 16:56:29 2017 -0800
@@ -47,7 +47,7 @@
                 sv |= poison
                 if v in nodes:
                     # history is linear
-                    return set([v])
+                    return {v}
         if sv < poison:
             for p in pfunc(v):
                 sp = seen[p]
@@ -151,7 +151,7 @@
 
     def hasbases(self):
         '''whether the common set has any non-trivial bases'''
-        return self.bases and self.bases != set([nullrev])
+        return self.bases and self.bases != {nullrev}
 
     def addbases(self, newbases):
         '''grow the ancestor set by adding new bases'''