builtin/submodule--helper: factor out submodule updating

diff --git a/t/t4012-diff-binary.sh b/t/t4012-diff-binary.sh
index 0a8af76aabf5ad79193341d1ffd4be4c9d4cb7a6..6579c81216a9b2e7dc6f2457cc46003dd905aa30 100755 (executable)
--- a/t/t4012-diff-binary.sh
+++ b/t/t4012-diff-binary.sh
@@ -102,10 +102,8 @@ test_expect_success 'apply binary patch' '
 
 test_expect_success 'diff --no-index with binary creation' '
        echo Q | q_to_nul >binary &&
-       (: hide error code from diff, which just indicates differences
-        git diff --binary --no-index /dev/null binary >current ||
-        true
-       ) &&
+       # hide error code from diff, which just indicates differences
+       test_might_fail git diff --binary --no-index /dev/null binary >current &&
        rm binary &&
        git apply --binary <current &&
        echo Q >expected &&