diff -r 7a9c905e51f9 -r 42a91897f090 mercurial/cmdutil.py
--- a/mercurial/cmdutil.py	Thu Apr 12 21:33:47 2018 +0900
+++ b/mercurial/cmdutil.py	Thu Apr 12 21:47:17 2018 +0900
@@ -1526,7 +1526,7 @@
 # it is given two arguments (sequencenumber, changectx)
 extraexportmap = {}
 
-def _exportsingle(repo, ctx, match, switch_parent, rev, seqno, write, diffopts):
+def _exportsingle(repo, ctx, match, switch_parent, seqno, write, diffopts):
     node = scmutil.binnode(ctx)
     parents = [p.node() for p in ctx.parents() if p]
     branch = ctx.branch()
@@ -1611,7 +1611,7 @@
         if not dest.startswith('<'):
             repo.ui.note("%s\n" % dest)
         _exportsingle(
-            repo, ctx, match, switch_parent, rev, seqno, write, opts)
+            repo, ctx, match, switch_parent, seqno, write, opts)
         if fo is not None:
             fo.close()