diff -r 8e72f9152c4d -r 010179e21e91 mercurial/filemerge.py
--- a/mercurial/filemerge.py	Wed Dec 06 22:56:15 2017 -0500
+++ b/mercurial/filemerge.py	Fri Dec 01 00:07:23 2017 -0800
@@ -469,7 +469,7 @@
     # calls might be depending on.
     from . import context
     if isinstance(fcd, context.overlayworkingfilectx):
-        fcd.ctx().flushall()
+        fcd.changectx().flushall()
 
     util.writefile(a + ".local", fcd.decodeddata())
     repo.wwrite(fd + ".other", fco.data(), fco.flags())