kvm: Run bash with -e to exit in case of error

  The script were failing to generating the proof but it was continuing anyway.
  the set -e forces the script exit.

software/kvm/buildout.hash.cfg

@@ -35,7 +35,7 @@ md5sum = a463a5e3cd2287d275d6943c2a11b7e4
 
 [template-kvm-import-script]
 filename = template/kvm-import.sh.jinja2
-md5sum = e95b7e827179d1cf6fa998c4535f8cd8
+md5sum = 013725987114c82ca3fd11097d0a7f9f
 
 [template-kvm-export]
 filename = instance-kvm-export.cfg.jinja2

software/kvm/template/kvm-import.sh.jinja2

 #!/bin/bash
 
+set -e
+
 VM_DIR={{ directory['srv'] }}
 BACKUP_DIR={{ directory['backup'] }}
 VM_FILE=virtual.qcow2