t6026: ensure that long-running script really is

When making sure that background tasks are cleaned up in 5babb5b
(t6026-merge-attr: clean up background process at end of test case,
2016-09-07), we considered to let the background task sleep longer, just
to be certain that it will still be running when we want to kill it
after the test.

Sadly, the assumption appears not to hold true that the test case passes
quickly enough to kill the background task within a second.

Simply increase it to an hour. No system can be possibly slow enough to
make above-mentioned assumption incorrect.

Reported by Andreas Schwab.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t6026-merge-attr.sh

@@ -183,16 +183,16 @@ test_expect_success 'up-to-date merge without common ancestor' '
 
 test_expect_success 'custom merge does not lock index' '
 	git reset --hard anchor &&
-	write_script sleep-one-second.sh <<-\EOF &&
-		sleep 1 &
+	write_script sleep-an-hour.sh <<-\EOF &&
+		sleep 3600 &
 		echo $! >sleep.pid
 	EOF
 	test_when_finished "kill \$(cat sleep.pid)" &&
 
 	test_write_lines >.gitattributes \
-		"* merge=ours" "text merge=sleep-one-second" &&
+		"* merge=ours" "text merge=sleep-an-hour" &&
 	test_config merge.ours.driver true &&
-	test_config merge.sleep-one-second.driver ./sleep-one-second.sh &&
+	test_config merge.sleep-an-hour.driver ./sleep-an-hour.sh &&
 	git merge master
 '