Here's the corresponding man page change to go with the proposal. Line 1770 of sftp.c already looked for the -l argument.
/Lars # diff sftp.1 sftp.1.old 41d40 < .Op Fl l Ar login_name 161,164d159 < .It Fl l Ar login_name < Specifies the user to log in as on the remote machine. This also may < be specified on a per-host basis in the configuration file.
