diff -r 31f42e683321 -r 76f938ec68a5 mercurial/commands.py
--- a/mercurial/commands.py	Wed May 03 23:50:41 2017 -0700
+++ b/mercurial/commands.py	Fri May 05 04:41:45 2017 +0530
@@ -706,7 +706,8 @@
 
     def commitfunc(ui, repo, message, match, opts):
         editform = 'backout'
-        e = cmdutil.getcommiteditor(editform=editform, **opts)
+        e = cmdutil.getcommiteditor(editform=editform,
+                                    **pycompat.strkwargs(opts))
         if not message:
             # we don't translate commit messages
             message = "Backed out changeset %s" % short(node)
@@ -2240,7 +2241,8 @@
     if not opts.get('date') and opts.get('currentdate'):
         opts['date'] = "%d %d" % util.makedate()
 
-    editor = cmdutil.getcommiteditor(editform='graft', **opts)
+    editor = cmdutil.getcommiteditor(editform='graft',
+                                     **pycompat.strkwargs(opts))
 
     cont = False
     if opts.get('continue'):
@@ -5216,7 +5218,8 @@
             editform = 'tag.remove'
         else:
             editform = 'tag.add'
-        editor = cmdutil.getcommiteditor(editform=editform, **opts)
+        editor = cmdutil.getcommiteditor(editform=editform,
+                                         **pycompat.strkwargs(opts))
 
         # don't allow tagging the null rev
         if (not opts.get('remove') and