diff -r 4950ae4d034f -r 566daffc607d mercurial/exchange.py
--- a/mercurial/exchange.py	Wed Jul 19 13:17:49 2017 -0700
+++ b/mercurial/exchange.py	Wed Apr 03 11:21:27 2019 -0700
@@ -707,8 +707,8 @@
 
     remotebookmark = listkeys(remote, 'bookmarks')
 
-    explicit = set([repo._bookmarks.expandname(bookmark)
-                    for bookmark in pushop.bookmarks])
+    explicit = {repo._bookmarks.expandname(bookmark)
+                for bookmark in pushop.bookmarks}
 
     remotebookmark = bookmod.unhexlifybookmarks(remotebookmark)
     comp = bookmod.comparebookmarks(repo, repo._bookmarks, remotebookmark)