diff -r a9ea2b1e5c4b -r 6ca5f825a0ca mercurial/pycompat.py
--- a/mercurial/pycompat.py	Sat Mar 24 14:13:37 2018 +0900
+++ b/mercurial/pycompat.py	Sat Mar 24 14:24:32 2018 +0900
@@ -243,6 +243,8 @@
     def open(name, mode='r', buffering=-1, encoding=None):
         return builtins.open(name, sysstr(mode), buffering, encoding)
 
+    safehasattr = _wrapattrfunc(builtins.hasattr)
+
     def _getoptbwrapper(orig, args, shortlist, namelist):
         """
         Takes bytes arguments, converts them to unicode, pass them to
@@ -326,6 +328,11 @@
     def getdoc(obj):
         return getattr(obj, '__doc__', None)
 
+    _notset = object()
+
+    def safehasattr(thing, attr):
+        return getattr(thing, attr, _notset) is not _notset
+
     def _getoptbwrapper(orig, args, shortlist, namelist):
         return orig(args, shortlist, namelist)