diff -r b24cde12061b -r b9bbcf9ffac1 mercurial/obsolete.py
--- a/mercurial/obsolete.py	Wed Feb 21 17:21:10 2018 +0100
+++ b/mercurial/obsolete.py	Tue Mar 13 20:34:38 2018 +0800
@@ -148,38 +148,8 @@
 
     return _getoptionvalue(repo, option)
 
-### obsolescence marker flag
-
-## bumpedfix flag
-#
-# When a changeset A' succeed to a changeset A which became public, we call A'
-# "bumped" because it's a successors of a public changesets
-#
-# o    A' (bumped)
-# |`:
-# | o  A
-# |/
-# o    Z
-#
-# The way to solve this situation is to create a new changeset Ad as children
-# of A. This changeset have the same content than A'. So the diff from A to A'
-# is the same than the diff from A to Ad. Ad is marked as a successors of A'
-#
-# o   Ad
-# |`:
-# | x A'
-# |'|
-# o | A
-# |/
-# o Z
-#
-# But by transitivity Ad is also a successors of A. To avoid having Ad marked
-# as bumped too, we add the `bumpedfix` flag to the marker. <A', (Ad,)>.
-# This flag mean that the successors express the changes between the public and
-# bumped version and fix the situation, breaking the transitivity of
-# "bumped" here.
-bumpedfix = 1
-usingsha256 = 2
+bumpedfix = obsutil.bumpedfix
+usingsha256 = obsutil.usingsha256
 
 ## Parsing and writing of version "0"
 #