debian/rules: show testsuite.log when tests are failing

Change-Id: I4cc6589d4ce95538baf3f30079a3af53cc218268
diff --git a/debian/rules b/debian/rules
index 4fe1f46..dbe582b 100755
--- a/debian/rules
+++ b/debian/rules
@@ -59,3 +59,7 @@
 	dh_strip --dbg-package=osmo-sgsn-dbg
 	dh_strip --dbg-package=osmo-gtphub-dbg
 	dh_strip --dbg-package=osmo-gbproxy-dbg
+
+# Print test results in case of a failure
+override_dh_auto_test:
+	dh_auto_test || (find . -name testsuite.log -exec cat {} \; ; false)