Guard setup with test_expect_success. Use test_might_fail
instead of ignoring the exit code from git config --unset.
Point out setup commands that are shared by multiple tests,
to make it easy to write GIT_SKIP_TESTS specifications that
work.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>