Use correct auth finder

lib/api/session.rb

@@ -11,12 +11,7 @@ module API
     # Example Request:
     #  POST /session
     post "/session" do
-      user, _ = Gitlab::Auth.find(
-        params[:email] || params[:login],
-        params[:password],
-        project: nil,
-        ip: request.ip
-      )
+      user = Gitlab::Auth.find_by_master_or_ldap(params[:email] || params[:login], params[:password])
 
       return unauthorized! unless user
       present user, with: Entities::UserLogin

lib/gitlab/backend/grack_auth.rb

@@ -95,7 +95,7 @@ module Grack
     end
 
     def authenticate_user(login, password)
-      user, _ = Gitlab::Auth.new.find_by_master_or_ldap(login, password)
+      user = Gitlab::Auth.new.find_by_master_or_ldap(login, password)
 
       unless user
         user = oauth_access_token_check(login, password)