Using numeric uid in become_user

Hello,
I am getting a file list using find module.
For each file in the resulting list I need to perform certain action with become/become_user, user being the owner of the found file.
However find module (I guess stat as well) does not return owner username, but only owner numerical UID.
I tried to use UID in become_user in the form of “#{{ item.uid}}”, but it did not work.
What is the best way to approach this?

Thanks
Gregory

To clarify - I suspect do not get pw_name in find result value probably because these users are virtual and retrieved from mysql by nscd daemon. However system and and all software sees these usernames just fine.