Merge branch 'js/t6026-clean-up' into maint

A test spawned a short-lived background process, which sometimes
prevented the test directory from getting removed at the end of the
script on some platforms.

* js/t6026-clean-up:
  t6026-merge-attr: clean up background process at end of test case

t/t6026-merge-attr.sh

@@ -185,7 +185,9 @@ test_expect_success 'custom merge does not lock index' '
 	git reset --hard anchor &&
 	write_script sleep-one-second.sh <<-\EOF &&
 		sleep 1 &
+		echo $! >sleep.pid
 	EOF
+	test_when_finished "kill \$(cat sleep.pid)" &&
 
 	test_write_lines >.gitattributes \
 		"* merge=ours" "text merge=sleep-one-second" &&