--- a/mercurial/copies.py	Wed May 15 16:10:52 2019 -0700
+++ b/mercurial/copies.py	Wed Jan 09 15:54:45 2019 -0800
@@ -798,4 +798,5 @@
     for dst, src in pathcopies(repo[fromrev], repo[rev]).iteritems():
         if dst in exclude:
             continue
-        wctx[dst].markcopied(src)
+        if dst in wctx:
+            wctx[dst].markcopied(src)