--- a/mercurial/wireprotov1server.py	Wed Jul 19 13:17:49 2017 -0700
+++ b/mercurial/wireprotov1server.py	Wed Apr 03 11:21:27 2019 -0700
@@ -345,7 +345,7 @@
       one specific branch of many.
     """
     def decodehexstring(s):
-        return set([binascii.unhexlify(h) for h in s.split(';')])
+        return {binascii.unhexlify(h) for h in s.split(';')}
 
     manifest = repo.vfs.tryread('pullbundles.manifest')
     if not manifest: