fix mass_update: add pipefail so make errors stop the update script

tools/utun_update.sh

@@ -1,5 +1,5 @@
 #!/bin/sh
-set -e
+set -eo pipefail
 
 # utun_update.sh - Remote uTun update script
 # Usage: ./tools/utun_update.sh [fast|full] [workdir]