[6.0] 2fdb50bae Add test case by @rezan for #2976.

[Dridi Boukelmoune]

commit 2fdb50bae533c0c04c3916bfcbb83d22766d768e
Author: Martin Blix Grydeland <martin at varnish-software.com>
Date:   Tue Apr 23 15:32:00 2019 +0200

    Add test case by @rezan for #2976.

diff --git a/bin/varnishtest/tests/r02976.vtc b/bin/varnishtest/tests/r02976.vtc
new file mode 100644
index 000000000..421cb3fe9
--- /dev/null
+++ b/bin/varnishtest/tests/r02976.vtc
@@ -0,0 +1,53 @@
+varnishtest "Detect probe interval inversion"
+
+barrier bprobe cond 2
+
+server s1 {
+	# 5 probe requests
+	rxreq
+	txresp
+	close
+	accept
+	rxreq
+	txresp
+	close
+	accept
+	rxreq
+	txresp
+	close
+	accept
+	rxreq
+	txresp
+	close
+	accept
+	rxreq
+	txresp
+	close
+	accept
+	barrier bprobe sync
+} -start
+
+varnish v1 -vcl {
+	backend b1 {
+		.host = "${s1_addr}";
+		.port = "${s1_port}";
+		.probe = {
+			.interval = 1s;
+		}
+	}
+
+	backend b2 {
+		.host = "${bad_ip}";
+		.probe = {
+			.interval = 24h;
+		}
+	}
+
+	sub vcl_recv {
+		if (!req.url) {
+			set req.backend_hint = b2;
+		}
+	}
+} -start
+
+barrier bprobe sync
\ No newline at end of file