--- a/mercurial/patch.py	Wed Nov 12 23:44:17 2014 -0800
+++ b/mercurial/patch.py	Wed Nov 12 23:47:25 2014 -0800
@@ -1564,6 +1564,8 @@
             v = opts.get(key)
             if v:
                 return v
+        if forceplain is not None and ui.plain():
+            return forceplain
         return getter(section, name or key, None, untrusted=untrusted)
 
     return mdiff.diffopts(