pyupgrade: drop redundant `open()` modes On one hand, this gets rid of some py2 cruft (like `U` and `t` modes). OTOH, I like being explict. But there's no way to disable individual transformations (and this change is part of `_fix_tokens()`, which is even harder to selectively use locally), and I'd rather have less noise when using `pyupgrade`. Warning: `contrib/synthrepo.py` appears not to have been updated to py3, as it's passing str to `error.Abort`. But since it was opening the file in unicode on py2, this change is a no-op.

--- a/mercurial/crecord.py	Mon Jan 06 01:44:46 2025 -0500
+++ b/mercurial/crecord.py	Tue Jan 07 17:28:46 2025 -0500
@@ -623,7 +623,7 @@
     chunkselector.stdscr = dummystdscr()
     if testfn and os.path.exists(testfn):
         # This file is purposely NOT opened in binary mode
-        with open(testfn, 'r') as testf:
+        with open(testfn) as testf:
             testcommands = [x.rstrip('\n') for x in testf.readlines()]
 
         while True: