diff -r 255f635c3204 -r 036e4483d3a1 mercurial/formatter.py
--- a/mercurial/formatter.py	Sun Mar 11 21:05:29 2018 +0900
+++ b/mercurial/formatter.py	Sun Mar 11 21:12:02 2018 +0900
@@ -508,6 +508,9 @@
     }
 
     def getsome(context, mapping, key):
+        v = mapping.get(key)
+        if v is not None:
+            return v
         return resmap.get(key)
 
     return {