When in the middle of t7063, we are sure untracked cache is supported,
so we can use --force-untracked-cache to skip the support detection
phase and save a few seconds. It's also good that --force-untracked-cache
is exercised in the test suite.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>