t1400: use consistent style for test_expect_success calls

Structure calls as

    test_expect_success 'description' '
    	body
    '

Use double quotes for the description if it requires parameter
expansion or contains a single quote.

Signed-off-by: Kyle Meyer <kyle@kyleam.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: kyleam