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

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

  EXTENSION[.COMMAND][.ROUTE]

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

In this patch, COMMAND and ROUTE are omitted.

hgext/transplant.py

@@ -86,7 +86,7 b' class transplanter(object):'
         self.opener = scmutil.opener(self.path)
         self.transplants = transplants(self.path, 'transplants',
                                        opener=self.opener)
-        self.editor = cmdutil.getcommiteditor(**opts)
+        self.editor = cmdutil.getcommiteditor(editform='transplant', **opts)
 
     def applied(self, repo, node, parent):
         '''returns True if a node is already an ancestor of parent