diff -r da510d1aa683 -r e11a0e6a17c1 Lib/unittest/mock.py
--- a/Lib/unittest/mock.py	Fri Dec 09 09:35:49 2016 +0100
+++ b/Lib/unittest/mock.py	Fri Dec 09 18:08:38 2016 +0800
@@ -104,26 +104,16 @@
 
 
 def _copy_func_details(func, funcopy):
-    funcopy.__name__ = func.__name__
-    funcopy.__doc__ = func.__doc__
-    try:
-        funcopy.__text_signature__ = func.__text_signature__
-    except AttributeError:
-        pass
     # we explicitly don't copy func.__dict__ into this copy as it would
     # expose original attributes that should be mocked
-    try:
-        funcopy.__module__ = func.__module__
-    except AttributeError:
-        pass
-    try:
-        funcopy.__defaults__ = func.__defaults__
-    except AttributeError:
-        pass
-    try:
-        funcopy.__kwdefaults__ = func.__kwdefaults__
-    except AttributeError:
-        pass
+    for attribute in (
+            "__name__", "__doc__", "__text_signature__",
+            "__module__", "__defaults__", "__kwdefaults__",
+    ):
+        try:
+            setattr(funcopy, attribute, getattr(func, attribute))
+        except AttributeError:
+            pass
 
 
 def _callable(obj):