[api] Move shared code to separate method

Moves code that handles marking succeeded logins to a separate method.
This DRYs the code a bit.

Cherry-picked from: c311c8e7

src/api/app/models/user.rb

@@ -238,10 +238,7 @@ class User < ActiveRecord::Base
     if ldap_info
       # We've found an ldap authenticated user - find or create an OBS userDB entry.
       if user
-        # stuff without affect to update_at
-        user.last_logged_in_at = Time.now
-        user.login_failure_count = 0
-        self.execute_without_timestamps { user.save! }
+        user.mark_login!
 
         # Check for ldap updates
         if user.email != ldap_info[0] || user.realname != ldap_info[1]
@@ -288,9 +285,7 @@ class User < ActiveRecord::Base
 
     # If the user could be found and the passwords equal then return the user
     if user && user.password_equals?(password)
-      user.last_logged_in_at = Time.now
-      user.login_failure_count = 0
-      self.execute_without_timestamps { user.save! }
+      user.mark_login!
 
       return user
     end
@@ -1042,6 +1037,12 @@ class User < ActiveRecord::Base
     User.update_notifications(params, self)
   end
 
+  def mark_login!
+    user.last_logged_in_at = Time.now
+    user.login_failure_count = 0
+    User.execute_without_timestamps { user.save! }
+  end
+
   private
 
   def can_modify_project_internal(project, ignoreLock)