diff -r 4f3e989536c3 -r 29dd37a418aa mercurial/policy.py
--- a/mercurial/policy.py	Mon Feb 12 16:09:31 2018 +0100
+++ b/mercurial/policy.py	Thu Jan 25 21:16:28 2018 -0500
@@ -71,7 +71,7 @@
 # keep in sync with "version" in C modules
 _cextversions = {
     (r'cext', r'base85'): 1,
-    (r'cext', r'bdiff'): 1,
+    (r'cext', r'bdiff'): 2,
     (r'cext', r'diffhelpers'): 1,
     (r'cext', r'mpatch'): 1,
     (r'cext', r'osutil'): 3,