fixed oauth login redirect when using app sub url

conf/grafana.dev.ini

@@ -3,7 +3,6 @@ app_mode = development
 [server]
 router_logging = false
 static_root_path = grafana/src
-root_url = %(protocol)s://%(domain)s:%(http_port)s/
 
 [oauth]
 enabled = true

pkg/api/login_oauth.go

@@ -76,5 +76,5 @@ func OAuthLogin(ctx *middleware.Context) {
 	// login
 	loginUserWithAccount(userQuery.Result, ctx)
 
-	ctx.Redirect("/")
+	ctx.Redirect(setting.AppSubUrl + "/")
 }