make dupsigs test less timing-sensitive

the dupsigs test is prone to failing on slow CI machines
because the first test can occur before the zone is fully
signed.

instead of just waiting ten seconds arbitrarily, we now
check every second, and allow up to 30 seconds before giving
up.

bin/tests/system/dupsigs/tests.sh

@@ -12,13 +12,30 @@
 . ../conf.sh
 
 status=0
+
+# Wait for the zone to be fully signed before beginning test
+#
+# We expect the zone to have the following:
+#
+# - 5 signatures for signing.test.
+# - 3 signatures for ns.signing.test.
+# - 2 x 500 signatures for a{0000-0499}.signing.test.
+#
+# for a total of 1008.
+fully_signed () {
+        $DIG axfr signing.test -p ${PORT} @10.53.0.1 |
+                awk 'BEGIN { lines = 0 }
+                     $4 == "RRSIG" {lines++}
+                     END { if (lines != 1008) exit(1) }'
+}
+retry_quiet 30 fully_signed || ret=1
+
 start=`date +%s`
-end=`expr $start + 150`
-sleep 10  # wait for a bit for the initial signing
-now=`expr $start + 10`
-while test $now -lt $end
-do
-	et=`expr $now - $start`
+now=$start
+end=$((start + 140))
+
+while [ $now -lt $end ]; do
+        et=$((now - start))
 	echo "=============== $et ============"
 	$JOURNALPRINT ns1/signing.test.db.signed.jnl | $PERL check_journal.pl
 	$DIG axfr signing.test -p ${PORT} @10.53.0.1 > dig.out.at$et
@@ -27,7 +44,7 @@ do
 	if [ ${et} -ne 0 -a ${lines} -ne 1008 ]
 	then
 		echo_i "failed"
-		status=`expr $status + 1`
+                status=$((status + 1))
 	fi
 	sleep 5
 	now=`date +%s`