codereview: update use of promptchoice for Mercurial 2.7

Fixes #6186.

R=golang-dev, bradfitz, remyoudompheng, rsc
CC=golang-dev
https://golang.org/cl/13112043

lib/codereview/codereview.py

@@ -712,6 +712,9 @@ Examples:
 '''
 
 def promptyesno(ui, msg):
+	if hgversion >= "2.7":
+		return ui.promptchoice(msg + " $$ &yes $$ &no", 0) == 0
+	else:
 		return ui.promptchoice(msg, ["&yes", "&no"], 0) == 0
 
 def promptremove(ui, repo, f):