diff -r c2e284cee333 -r eef9a2d67051 mercurial/__init__.py
--- a/mercurial/__init__.py	Sun Oct 06 13:17:19 2019 -0400
+++ b/mercurial/__init__.py	Sun Oct 06 13:28:56 2019 -0400
@@ -172,7 +172,7 @@
                 l = (
                     b'; from mercurial.pycompat import '
                     b'delattr, getattr, hasattr, setattr, '
-                    b'open, unicode\n'
+                    b'unicode\n'
                 )
                 for u in tokenize.tokenize(io.BytesIO(l).readline):
                     if u.type in (tokenize.ENCODING, token.ENDMARKER):
@@ -221,7 +221,7 @@
     # ``replacetoken`` or any mechanism that changes semantics of module
     # loading is changed. Otherwise cached bytecode may get loaded without
     # the new transformation mechanisms applied.
-    BYTECODEHEADER = b'HG\x00\x0c'
+    BYTECODEHEADER = b'HG\x00\x0d'
 
     class hgloader(importlib.machinery.SourceFileLoader):
         """Custom module loader that transforms source code.