t/t5538-push-shallow.sh: use the $( ... ) construct for command substitution

diff --git a/t/t4027-diff-submodule.sh b/t/t4027-diff-submodule.sh
index 241a74d2a20276d711944d3e203083b515486e77..518bf9524e0b55181f3c440d202b69c12a0b314f 100755 (executable)
--- a/t/t4027-diff-submodule.sh
+++ b/t/t4027-diff-submodule.sh
@@ -5,7 +5,6 @@ test_description='difference in submodules'
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/diff-lib.sh
 
-_z40=0000000000000000000000000000000000000000
 test_expect_success setup '
        test_tick &&
        test_create_repo sub &&