diff --git a/mercurial/__init__.py b/mercurial/__init__.py
--- a/mercurial/__init__.py
+++ b/mercurial/__init__.py
@@ -110,65 +110,14 @@
             except IndexError:
                 return False
 
-        def _findargnofcall(n):
-            """Find arg n of a call expression (start at 0)
-
-            Returns index of the first token of that argument, or None if
-            there is not that many arguments.
-
-            Assumes that token[i + 1] is '('.
-
-            """
-            nested = 0
-            for j in range(i + 2, len(tokens)):
-                if _isop(j, ')', ']', '}'):
-                    # end of call, tuple, subscription or dict / set
-                    nested -= 1
-                    if nested < 0:
-                        return None
-                elif n == 0:
-                    # this is the starting position of arg
-                    return j
-                elif _isop(j, '(', '[', '{'):
-                    nested += 1
-                elif _isop(j, ',') and nested == 0:
-                    n -= 1
-
-            return None
-
-        def _ensureunicode(j):
-            """Make sure the token at j is a unicode string
-
-            This rewrites a string token to include the unicode literal prefix
-            so the string transformer won't add the byte prefix.
-
-            Ignores tokens that are not strings. Assumes bounds checking has
-            already been done.
-
-            """
-            st = tokens[j]
-            if st.type == token.STRING and st.string.startswith(("'", '"')):
-                tokens[j] = st._replace(string='u%s' % st.string)
-
         for i, t in enumerate(tokens):
             # This looks like a function call.
             if t.type == token.NAME and _isop(i + 1, '('):
                 fn = t.string
 
-                # *attr() builtins don't accept byte strings to 2nd argument.
-                if fn in (
-                    'getattr',
-                    'setattr',
-                    'hasattr',
-                    'safehasattr',
-                ) and not _isop(i - 1, '.'):
-                    arg1idx = _findargnofcall(1)
-                    if arg1idx is not None:
-                        _ensureunicode(arg1idx)
-
                 # It changes iteritems/values to items/values as they are not
                 # present in Python 3 world.
-                elif fn in ('iteritems', 'itervalues') and not (
+                if fn in ('iteritems', 'itervalues') and not (
                     tokens[i - 1].type == token.NAME
                     and tokens[i - 1].string == 'def'
                 ):
@@ -182,7 +131,7 @@
     # ``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\x13'
+    BYTECODEHEADER = b'HG\x00\x14'
 
     class hgloader(importlib.machinery.SourceFileLoader):
         """Custom module loader that transforms source code.
diff --git a/mercurial/keepalive.py b/mercurial/keepalive.py
--- a/mercurial/keepalive.py
+++ b/mercurial/keepalive.py
@@ -255,7 +255,7 @@
         # If not a persistent connection, don't try to reuse it. Look
         # for this using getattr() since vcr doesn't define this
         # attribute, and in that case always close the connection.
-        if getattr(r, r'will_close', True):
+        if getattr(r, 'will_close', True):
             self._cm.remove(h)
 
         if DEBUG:
diff --git a/mercurial/policy.py b/mercurial/policy.py
--- a/mercurial/policy.py
+++ b/mercurial/policy.py
@@ -70,7 +70,7 @@
     except AttributeError:
         raise ImportError(r'cannot import name %s' % modname)
     # force import; fakelocals[modname] may be replaced with the real module
-    getattr(mod, r'__doc__', None)
+    getattr(mod, '__doc__', None)
     return fakelocals[modname]
 
 
@@ -94,7 +94,7 @@
 
 def _checkmod(pkgname, modname, mod):
     expected = _cextversions.get((pkgname, modname))
-    actual = getattr(mod, r'version', None)
+    actual = getattr(mod, 'version', None)
     if actual != expected:
         raise ImportError(
             r'cannot import module %s.%s '
diff --git a/mercurial/pycompat.py b/mercurial/pycompat.py
--- a/mercurial/pycompat.py
+++ b/mercurial/pycompat.py
@@ -270,7 +270,7 @@
     def getdoc(obj):
         """Get docstring as bytes; may be None so gettext() won't confuse it
         with _('')"""
-        doc = getattr(obj, u'__doc__', None)
+        doc = getattr(obj, '__doc__', None)
         if doc is None:
             return doc
         return sysbytes(doc)
diff --git a/mercurial/testing/storage.py b/mercurial/testing/storage.py
--- a/mercurial/testing/storage.py
+++ b/mercurial/testing/storage.py
@@ -24,7 +24,7 @@
 
 
 class basetestcase(unittest.TestCase):
-    if not getattr(unittest.TestCase, r'assertRaisesRegex', False):
+    if not getattr(unittest.TestCase, 'assertRaisesRegex', False):
         assertRaisesRegex = (  # camelcase-required
             unittest.TestCase.assertRaisesRegexp
         )
diff --git a/mercurial/util.py b/mercurial/util.py
--- a/mercurial/util.py
+++ b/mercurial/util.py
@@ -623,7 +623,7 @@
     def _fillbuffer(self):
         res = super(observedbufferedinputpipe, self)._fillbuffer()
 
-        fn = getattr(self._input._observer, r'osread', None)
+        fn = getattr(self._input._observer, 'osread', None)
         if fn:
             fn(res, _chunksize)
 
@@ -634,7 +634,7 @@
     def read(self, size):
         res = super(observedbufferedinputpipe, self).read(size)
 
-        fn = getattr(self._input._observer, r'bufferedread', None)
+        fn = getattr(self._input._observer, 'bufferedread', None)
         if fn:
             fn(res, size)
 
@@ -643,7 +643,7 @@
     def readline(self, *args, **kwargs):
         res = super(observedbufferedinputpipe, self).readline(*args, **kwargs)
 
-        fn = getattr(self._input._observer, r'bufferedreadline', None)
+        fn = getattr(self._input._observer, 'bufferedreadline', None)
         if fn:
             fn(res)