Only perform login action on explicit POST (#25653).

Patch by Holger Just.

git-svn-id: http://svn.redmine.org/redmine/trunk@16554 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/controllers/account_controller.rb

@@ -34,12 +34,12 @@ class AccountController < ApplicationController
 
   # Login request and validation
   def login
-    if request.get?
+    if request.post?
+      authenticate_user
+    else
       if User.current.logged?
         redirect_back_or_default home_url, :referer => true
       end
-    else
-      authenticate_user
     end
   rescue AuthSourceException => e
     logger.error "An error occurred when authenticating #{params[:username]}: #{e.message}"