--- a/hgext/uncommit.py	Wed Mar 13 20:09:56 2019 -0700
+++ b/hgext/uncommit.py	Tue Mar 19 22:58:39 2019 -0700
@@ -83,7 +83,7 @@
         mctx = context.memfilectx(repo, memctx, fctx.path(), fctx.data(),
                                   fctx.islink(),
                                   fctx.isexec(),
-                                  copied=copied.get(path))
+                                  copysource=copied.get(path))
         return mctx
 
     if not files: