[BUG] test suite broken with GIT_TEST_SPLIT_INDEX

[Thomas Gummerer <t.gummerer@gmail.com>]

Hi,

I just tried to run the test suite with GIT_TEST_SPLIT_INDEX=YesPlease
and noticed that a few tests are broken both in pu and master.

Below the test failures on master:

Test Summary Report
-------------------
t7009-filter-branch-null-sha1.sh                 (Wstat: 256 Tests: 5 Failed: 2)
  Failed tests:  4-5
  Non-zero exit status: 1
t3900-i18n-commit.sh                             (Wstat: 256 Tests: 34 Failed: 1)
  Failed test:  34
  Non-zero exit status: 1
t5407-post-rewrite-hook.sh                       (Wstat: 256 Tests: 14 Failed: 4)
  Failed tests:  11-14
  Non-zero exit status: 1
t3415-rebase-autosquash.sh                       (Wstat: 256 Tests: 19 Failed: 15)
  Failed tests:  4-17, 19
  Non-zero exit status: 1
t3404-rebase-interactive.sh                      (Wstat: 256 Tests: 95 Failed: 54)
  Failed tests:  18, 20, 22-24, 26-43, 45, 47-74, 84-85
  Non-zero exit status: 1

Bisecting between master and v2.10.0 leads me to the merge commit
94c9b5af70 ("Merge branch 'cc/split-index-config'", 2017-03-17).

Unfortunately I don't forsee myself having time to track the bug down
soon.  Sorry for not noticing this earlier in the cycle.

The bisect log is below if someone finds it helpful:

git bisect start
# bad: [6a2c2f8d34fa1e8f3bb85d159d354810ed63692e] Git 2.13-rc0
git bisect bad 6a2c2f8d34fa1e8f3bb85d159d354810ed63692e
# good: [6ebdac1bab966b720d776aa43ca188fe378b1f4b] Git 2.10
git bisect good 6ebdac1bab966b720d776aa43ca188fe378b1f4b
# good: [733671b0fd2fb03edb05273f36ec70bd624e544f] Merge branch 'maint'
git bisect good 733671b0fd2fb03edb05273f36ec70bd624e544f
# good: [04b4f7d579056cedaae2de0a019e5993b4d9c2d0] Merge branch 'sb/submodule-update-initial-runs-custom-script' into maint
git bisect good 04b4f7d579056cedaae2de0a019e5993b4d9c2d0
# bad: [af6865a7f1e1d915d3b63e998226028ca4abb6ee] submodule.c: convert is_submodule_modified to use strbuf_getwholeline
git bisect bad af6865a7f1e1d915d3b63e998226028ca4abb6ee
# good: [3f7ebc6ece46f1c23480d094688b8b5f24eb345c] Merge branch 'jk/tempfile-ferror-fclose-confusion'
git bisect good 3f7ebc6ece46f1c23480d094688b8b5f24eb345c
# bad: [94c9b5af703eb70adba349cfbfaaa3029849744c] Merge branch 'cc/split-index-config'
git bisect bad 94c9b5af703eb70adba349cfbfaaa3029849744c
# good: [36d5286f6815542761dae92fdcdce8db1556727f] Merge branch 'ax/line-log-range-merge-fix'
git bisect good 36d5286f6815542761dae92fdcdce8db1556727f
# good: [c3a008250272295271584c6303463ffb9b055cbc] read-cache: use freshen_shared_index() in read_index_from()
git bisect good c3a008250272295271584c6303463ffb9b055cbc
# good: [228b78752de9d759839665764391262c0ec156cf] Merge branch 'jt/perf-updates'
git bisect good 228b78752de9d759839665764391262c0ec156cf
# good: [073778017158ecf3153b050776029907bc75826f] Merge branch 'kn/ref-filter-branch-list'
git bisect good 073778017158ecf3153b050776029907bc75826f
# good: [b46013950aff31b6626af96ccbf2c48469e36c66] Documentation/git-update-index: explain splitIndex.*
git bisect good b46013950aff31b6626af96ccbf2c48469e36c66
# good: [32c43f595f93cdd4ed5305aef97a3f6aaa74ed72] Sync with 'maint'
git bisect good 32c43f595f93cdd4ed5305aef97a3f6aaa74ed72
# first bad commit: [94c9b5af703eb70adba349cfbfaaa3029849744c] Merge branch 'cc/split-index-config'