revset: avoid shadowing a variable with a list comprehension

revset: avoid shadowing a variable with a list comprehension

--- a/mercurial/revset.py	Thu Nov 10 16:34:43 2016 -0500
+++ b/mercurial/revset.py	Thu Nov 10 16:35:10 2016 -0500
@@ -437,10 +437,10 @@
 def func(repo, subset, a, b, order):
     f = getsymbol(a)
     if f in symbols:
-        fn = symbols[f]
-        if getattr(fn, '_takeorder', False):
-            return fn(repo, subset, b, order)
-        return fn(repo, subset, b)
+        func = symbols[f]
+        if getattr(func, '_takeorder', False):
+            return func(repo, subset, b, order)
+        return func(repo, subset, b)
 
     keep = lambda fn: getattr(fn, '__doc__', None) is not None