cleanup: run pyupgrade on our source tree to clean up varying things Built with: hg files 'set:**.py - mercurial/thirdparty/** - "contrib/python-zstandard/**" - hgext/fsmonitor/pywatchman/**' | xargs pyupgrade --keep-percent-format --keep-extraneous-parens and then blackened. pyupgrade comes from https://github.com/asottile/pyupgrade with a patch to let me preserve extraneous parens (which we use for marking strings that shouldn't be translated), and lets us clean up a bunch of idioms that have cruftily accumulated over the years. # skip-blame no-op automated code cleanups Differential Revision: https://phab.mercurial-scm.org/D8255

--- a/mercurial/ancestor.py	Fri Mar 06 10:52:44 2020 +0100
+++ b/mercurial/ancestor.py	Fri Mar 06 13:27:41 2020 -0500
@@ -138,7 +138,7 @@
         k = 0
         for i in interesting:
             k |= i
-        return set(n for (i, n) in mapping if k & i)
+        return {n for (i, n) in mapping if k & i}
 
     gca = commonancestorsheads(pfunc, *orignodes)