Allow errors to terminate the build

Change-Id: Ice15e942b57785566063181f9342fe344285f263
diff --git a/tools/build/onos-release b/tools/build/onos-release
index 42ad942..e841b3a 100755
--- a/tools/build/onos-release
+++ b/tools/build/onos-release
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/bash -ex
 # -----------------------------------------------------------------------------
 # Drives the ONOS release process.
 # -----------------------------------------------------------------------------