tag: pass 'editform' argument to 'cmdutil.getcommiteditor'

This patch passes 'editform' argument according to the format below:

  COMMAND[.ROUTE]

  - ROUTE: name of route, if there are two or more routes in COMMAND

In this patch, 'add' and 'remove' are used as ROUTE

mercurial/commands.py

@@ -5799,7 +5799,11 b' def tag(ui, repo, name1, *names, **opts)'
         if date:
             date = util.parsedate(date)
 
-        editor = cmdutil.getcommiteditor(**opts)
+        if opts.get('remove'):
+            editform = 'tag.remove'
+        else:
+            editform = 'tag.add'
+        editor = cmdutil.getcommiteditor(editform=editform, **opts)
 
         # don't allow tagging the null rev
         if (not opts.get('remove') and