t5607 fail with GIT_TEST_FAIL_PREREQS enabled

[Son Luong Ngoc <sluongng@gmail.com>]

Hi folks,

Our internal CI spotted a failing test when build from 'next' and
'master' branch

    git/t% GIT_TEST_FAIL_PREREQS=1 ./t5607-clone-bundle.sh
    ok 1 - setup
    ok 2 - "verify" needs a worktree
    ok 3 - annotated tags can be excluded by rev-list options
    ok 4 - die if bundle file cannot be created
    ok 5 - bundle --stdin
    ok 6 - bundle --stdin <rev-list options>
    ok 7 - empty bundle file is rejected
    not ok 8 - ridiculously long subject in boundary
    #
    #               >file4 &&
    #               test_tick &&
    #               git add file4 &&
    #               printf "%01200d\n" 0 | git commit -F - &&
    #               test_commit fifth &&
    #               git bundle create long-subject-bundle.bdl HEAD^..HEAD &&
    #               cat >expect <<-EOF &&
    #               $(git rev-parse main) HEAD
    #               EOF
    #               git bundle list-heads long-subject-bundle.bdl >actual &&
    #               test_cmp expect actual &&
    #
    #               git fetch long-subject-bundle.bdl &&
    #
    #               if ! test_have_prereq SHA1
    #               then
    #                       echo "@object-format=sha256"
    #               fi >expect &&
    #               cat >>expect <<-EOF &&
    #               -$(git log --pretty=format:"%H %s" -1 HEAD^)
    #               $(git rev-parse HEAD) HEAD
    #               EOF
    #
    #               if test_have_prereq SHA1
    #               then
    #                       head -n 3 long-subject-bundle.bdl
    #               else
    #                       head -n 4 long-subject-bundle.bdl
    #               fi | grep -v "^#" >actual &&
    #
    #               test_cmp expect actual
    #
    ok 9 - prerequisites with an empty commit message
    ok 10 - failed bundle creation does not leave cruft
    ok 11 - fetch SHA-1 from bundle
    ok 12 - git bundle uses expected default format
    ok 13 - git bundle v3 has expected contents
    ok 14 - git bundle v3 rejects unknown capabilities
    # failed 1 among 14 test(s)
    1..14

Cheers,
Son Luong.