update_manager_local_transfers_allowed()
Determines if file transfers will be performed locally.
If the server is configured such that webserver-created files have the same owner as the configuration directory (e.g., sites/default) where new code will eventually be installed, the update manager can transfer files entirely locally, without changing their ownership (in other words, without prompting the user for FTP, SSH or other credentials).
This server configuration is an inherent security wea