It can be necessary to disable SMTP authentication by a mechanism other
than sendemail.smtpuser being undefined. For example, if the user has
sendemail.smtpuser set globally but wants to disable authentication
locally in one repository.
--smtp-auth and sendemail.smtpauth now understand the value 'none' which
means to disable authentication completely, even if an authentication
user is specified.
The value 'none' is lower case to avoid conflicts with any RFC 4422
authentication mechanisms.
The user may also specify the command line argument --no-smtp-auth as a
shorthand for --smtp-auth=none
Signed-off-by: Joshua Watt <JPEWhacker@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>