diff -r d4a1bfe1de63 -r bed9e6c706f6 mercurial/templater.py
--- a/mercurial/templater.py	Thu Oct 01 23:13:57 2015 -0700
+++ b/mercurial/templater.py	Thu Oct 08 17:44:22 2015 -0500
@@ -237,8 +237,6 @@
             v = ''
     if callable(v):
         return v(**mapping)
-    if isinstance(v, types.GeneratorType):
-        v = list(v)
     return v
 
 def buildtemplate(exp, context):