py3: use pickle directly pycompat.pickle abstracted over the different pickle modules in Python 2 and 3. Now that we're Python 3 only, it is safe to use the `pickle` module directly. So this commit does that. As part of this we remove the rules from check-code.py that were forbidden direct pickle module use. We retain the `util.pickle` symbol for backwards compatibility, just in case some extensions were using it. Differential Revision: https://phab.mercurial-scm.org/D12249

--- a/mercurial/formatter.py	Wed Mar 02 17:51:27 2022 -0800
+++ b/mercurial/formatter.py	Tue Mar 01 20:29:03 2022 -0800
@@ -110,6 +110,7 @@
 import contextlib
 import itertools
 import os
+import pickle
 
 from .i18n import _
 from .node import (
@@ -133,8 +134,6 @@
     stringutil,
 )
 
-pickle = util.pickle
-
 
 def isprintable(obj):
     """Check if the given object can be directly passed in to formatter's