We had an instance of a git command in a non-assignment command
substitution. Its return code was lost so we would not be able to detect
if the command failed for some reason. Since we were testing to make
sure the output of the command was empty, rewrite it in a more canonical
way.

Signed-off-by: Denton Liu <redacted>
---
 t/t3419-rebase-patch-id.sh | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/t/t3419-rebase-patch-id.sh b/t/t3419-rebase-patch-id.sh
index 49f548cdb9..94552669ae 100755
--- a/t/t3419-rebase-patch-id.sh
+++ b/t/t3419-rebase-patch-id.sh

@@ -80,7 +80,8 @@ do_tests () {
 		git commit -q -m "change big file again" &&
 		git checkout -q other^{} &&
 		git rebase master &&
-		test_must_fail test -n "$(git rev-list master...HEAD~)"
+		git rev-list master...HEAD~ >revs &&
+		test_must_be_empty revs
 	'
 
 	test_expect_success $pr 'do not drop patch' '

-- 
2.24.1.810.g65a2f617f4