If --use-client-spec was given, set the matching configuration
variable. This is necessary to ensure that future submits
work properly.
The alternatives of requiring the user to set it, or providing
a command-line option on every submit, are error prone.
Signed-off-by: Pete Wyckoff <pw@padd.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>