'
test_expect_success 'replace submodule revision' '
+ invalid=$(test_oid numeric) &&
git reset --hard original &&
git filter-branch -f --tree-filter \
"if git ls-files --error-unmatch -- submod > /dev/null 2>&1
- then git update-index --cacheinfo 160000 0123456789012345678901234567890123456789 submod
+ then git update-index --cacheinfo 160000 $invalid submod
fi" HEAD &&
test $orig_head != $(git show-ref --hash --head HEAD)
'