This new configuration variable defines the default remote to push to,
and overrides `branch.<name>.remote` for all branches. It is useful
in the typical triangular-workflow setup, where the remote you're
fetching from is different from the remote you're pushing to.
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com> Reviewed-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>