diff -r 7ed0750c71a1 -r 50474f0b3f1b mercurial/changelog.py
--- a/mercurial/changelog.py	Mon Oct 02 19:28:41 2017 +0100
+++ b/mercurial/changelog.py	Mon Oct 02 11:03:53 2017 +0100
@@ -151,7 +151,7 @@
     manifest = attr.ib(default=nullid)
     user = attr.ib(default='')
     date = attr.ib(default=(0, 0))
-    files = attr.ib(default=[])
+    files = attr.ib(default=attr.Factory(list))
     description = attr.ib(default='')
 
 class changelogrevision(object):